123 pubblicazioni classificate nel seguente modo:

Effect of doping of organo-soluble carbon dots on ionic relaxation and conductivity of planar anchored cyanobiphenyl based nematic liquid crystal
JOURNAL OF MOLECULAR STRUCTURE
Autore/i: P, P.; Singh, A. K.; Malik, P.; Kumar, S.; Supreet, ; Gathania, A. K.; Prakash, J.; Castagna, R.; Lucchetta, D. E.; Malik, P.; Singh, G.
Classificazione: 1 Contributo su Rivista
Abstract: We demonstrate here the striking effect of organo-soluble carbon dots (CDs, diameter ∼7- 8 nm) on the tunability of ionic relaxation and conductivity of the host, planar anchored thermotropic nematic liquid crystal (5CB, 4-Cyano-4′-pentylbiphenyl). The optical texture, frequency, temperature, and concentration dependent dielectric studies of pristine 5CB and CDs-5CB composites have been performed using the polarising optical microscope and high-resolution dielectric spectroscopy, respectively. The doping of 0.5 wt% CDs into planar anchored 5CB is resulted into the vertical alignment confirmed through the cross-polarised optical microscope. The doping of CDs in 5CB liquid crystal is resulted into an unprecedented faster ionic relaxation with an abatement of the ionic amplitude at room temperature. The shift in the relaxation frequency for 0.5 wt% CDs-5CB composite (induced vertical alignment) as compared to pristine 5CB (planar aligned) at 28 °C (nematic) is found to be ∼13 folds which is further increased to ∼18 folds at 38 °C (isotropic). A similar trend in the conductivity curve is also observed which further confirms the significant enhancement in conductivity value with increase in temperature and concentration of dopant CDs. The observation of enhanced ionic conductivity and faster ionic relaxation in CDs-5CB composites as compared to pristine 5CB are attributed to the complete change of planar to vertical alignment by doping of CDs on planar anchored liquid crystal sample cells. It appears that the plausible strong interaction between hydrocarbon chains of CDs and 5CB molecules through anchored substrate surfaces with increasing concentration of CDs and decrease in rotational viscosity of host 5CB with increasing temperature certainly plays a pivotal role in the tuning of ionic relaxation and conductivity in the liquid crystal sample cells. We certainly believe that our results would catalyze the cognizance of the ionic relaxation and conductivity in CDs-5CB composites and other related systems. Moreover, such composites with tunable ionic relaxation/conductivity would be certainly helpful in the fabrication of various tuneable devices such as wave front corrector, low frequency oscillation generators, dynamic light scattering, and so on.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/328071

Short term effects of extremely low irradiance photobiomodulation on retinal function, in age related macular degeneration
EUROPEAN JOURNAL OF OPHTHALMOLOGY
Autore/i: Franceschelli, Sara; D’Andrea, Pierdomenico; Farina, Marco; Gallenga, Carla Enrica; Grilli, Alfredo; Pesce, Mirko; Di Donato, Andrea; Lucchetta, Daniele; Ambrosini, Giovanna; Benedetti, Stefano; Benedetti, Margherita; Lobefalo, Lucio
Classificazione: 1 Contributo su Rivista
Abstract: Background: recently much studies evidenced the potential role of photo-biomodulation (PBM) in patients affected by Age-related Macular Degeneration (AMD). We designed a new wearable device for self-medication that employs the same broadband red light described in literature, but with extremely low irradiance. Aim: to demonstrate the safety and effectiveness of low-fluence light stimulations emitted by a LED source with appropriate wavelengths through our new device in improving short-term visual function in patients affected by severe non neovascular AMD. Materials and methods: we prospectively enrolled patients affected by severe non-neovascular AMD with a relative sparing of the foveal region. All the patients were randomly assigned in placebo or in treatment group. The treatment consisted of 10 sessions of 10-min each, using the new device comprised of micro-LEDs that emitted light onto an amorphous support assembled within Metallic eyeglasses. The placebo group blindly underwent the same number of PBM sessions with the micro-LED turned off. Before and after each placebo/treatment sessions all the patients received: optical coherence tomography (OCT), Best-Corrected Visual Acuity (BCVA) and Microperimetry (MP). Results: no significant differences in the anatomical parameters were observed in the two groups. The MP mean sensitivity and the central visual function both far and near significantly improved in the treated group (respectively p < 0.001, p < 0.001) Conclusions: our pivotal demonstrated that the LED PBM delivered through our new device is a safe and effective tool for improving short-term visual function in patients affected by severe non-neovascular AMD.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/328053

Eco-friendly carbon dots induced thermally stable vertical alignment in planar anchored nematic liquid crystal
JOURNAL OF MOLECULAR LIQUIDS
Autore/i: Priscilla, P.; Varshney, D.; Prakash, J.; Kumar, S.; Singh, A.; Malik, P.; Supreet, ; Gathania, A. K.; Castagna, R.; Lucchetta, D. E.; Singh, G.
Classificazione: 1 Contributo su Rivista
Abstract: We report the induction of thermally stable vertical alignment of nematic liquid crystal, 4-cyano-4′-pentylbiphenyl (5CB), in a planar anchored cell by doping with eco-friendly carbon dots (CDs, diameter ∼7–8 nm), investigated through thermal, optical, electro-optical and dielectric spectroscopic techniques. Cross-polarized optical textures and voltage-dependent optical transmission measurements demonstrate the induction of vertical alignment of CDs-5CB composites with concentration of CDs (≥0.3 wt%) in planar anchored sample cells at room temperature. Moreover, the frequency-bias-concentration dependent dielectric studies done also confirms the induced vertical alignment. For instance, the relative dielectric permittivity measured on CDs-5CB composites (CDs ≥ 0.3 wt%) in planar anchored sample cells at bias voltage of 0 V and 30 V DC are almost equal and the presence of a short axis molecular relaxation at 0 V confirms the induced vertical alignment. The concentration and bias dependence of short axis molecular relaxation frequency are also discussed. It appears that CDs are able to align 5CB molecules vertically at the substrate by overcoming the pre-existing planar anchoring. Such induced alignment would propagate through the bulk of sample cell because of the coherence length of nematic liquid crystal molecules and eventually the whole sample obtains vertical alignment. We anticipate the great utility of these composites in the production of eco-friendly liquid crystal displays and other photonic devices, sensors, etc.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/324532

On the Use of Haloalkane/Acrylate-Based Holographic Gratings as Compression and Rotation Sensors
SENSORS
Autore/i: Castagna, R.; Riminesi, C.; Di Donato, A.; Francescangeli, O.; Lucchetta, D. E.
Classificazione: 1 Contributo su Rivista
Abstract: In this work, we test the effectiveness of using highly transparent holographic phase reflection and transmission volume gratings based on multifunctional acrylates as linear compression and rotation sensors. The gratings are recorded in a holographic mixture based on multi-reticulated acrylate and haloalkanes. To activate the photo-polymerization process, we used a mixture of 6-oxocamphore and rhodamine 6G. The mixture is a simplified version of the mixture used in previous works and shows some interesting features mainly in connection with the different roles played by the rhodamine 6G dye at different writing wavelengths (Formula presented.) = 532 nm and (Formula presented.) = 460 nm. Regarding reflection gratings, the maximum achieved diffraction efficiency is ≈50% and their use as linear compression sensors produces a shift in the reflection peak of 2 nm. Following the removal of compression, the grating slowly returns to the initial state. Regarding transmission gratings, the maximum achieved diffraction efficiency is ≈45% and they demonstrate very high sensitivity to even small rotations in a free-standing configuration.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/309987

Development of a Quartz-Based Photo-Mobile Polymer Film for Controlled Motion Triggered by Light or Heat
MATERIALS
Autore/i: Castagna, R.; Riminesi, C.; Pianesi, M. S.; Sabbatini, S.; Di Donato, A.; Singh, G.; Francescangeli, O.; Cantisani, E.; Castellini, P.; Lucchetta, D. E.
Classificazione: 1 Contributo su Rivista
Abstract: We have developed a photo-mobile polymer film, that combines organic and inorganic materials, to allow for controlled motion that can be triggered by light or heat. Our film is made using recycled quartz and consists of two layers: a multi-acrylate polymer layer and a layer containing oxidized 4-amino-phenol and N-Vinyl-1-Pyrrolidinone. The use of quartz in our film also gives it a high temperature resistance of at least 350 °C. When exposed to heat, the film moves in a direction that is independent of the heat source, due to its asymmetrical design. Once the heat source is removed, the film returns to its original position. ATR-FTIR measurements confirm this asymmetrical configuration. This technology may have potential applications in energy harvesting, due to the piezoelectric properties of quartz.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/316313

Feasibility study for the advanced characterization of musical string wires
Mechanical Technology and Structural Materials
Autore/i: Rogante, M.; Lakatos, G.; Lucchetta, D. E.; Nastovski, I.
Editore: Croatian Society for Mechanical Technologies
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: In chordophone musical instruments, each note played is the result of the vibration of a string or a series of two or more strings at a defined frequency, determined by the length, diameter, tension and density of the metal wire involved, as it is specific elastic element. The durability and performance of musical strings depend on numerous factors, including the quality of the constitutive materials, the production process and specific treatments. With the aim of enhancing the characteristics of these strings and avoiding problems such as corrosive phenomena or breakage events of the musical strings during the concert, the industry of the sector dedicates considerable attention to the analysis of possible technological methods capable of giving the same threads high qualitative and functional properties. This article, after a brief introduction on musical instrument strings and their inherent problems, concerns their possible advanced nano(micro)-characterization by neutron diffraction and small-angle neutron scattering. These techniques allow, in particular, to determine the residual strain and stresses and the crystallographic texture, and to identify and study important nano(micro)-defects such as matrix heterogeneity, porosity, gas bubbles and precipitates, among the main factors responsible for the wire's performances: thereby proving to be indispensable to completely study the structure and the effect of the constitutive materials' characteristics on the parameters of the acoustic properties.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/324533

Light-Controlled Rotational Speed of an Acoustically Levitating Photomobile Polymer Film
MATERIALS
Autore/i: Lucchetta, Daniele Eugenio; Castellini, Paolo; Martarelli, Milena; Scalise, Lorenzo; Pandarese, Giuseppe; Riminesi, Cristiano; Singh, Gautam; Di Donato, Andrea; Francescangeli, Oriano; Castagna, Riccardo
Classificazione: 1 Contributo su Rivista
Abstract: In this work, we study the light-induced changes of the rotational speed of a thin photomobile film using a single-axis acoustic levitator operating at 40 kHz. In our experiments, a 50 μm thick photomobile polymer film (PMP) is placed in one of the nodes of a stationary acoustic field. Under the action of the field, the film remains suspended in air. By externally perturbing this stable equilibrium condition, the film begins to rotate with its natural frequency. The rotations are detected in real time by monitoring the light of a low power He-Ne laser impinging on and reflected by the film itself. During the rotational motion, an external laser source is used to illuminate the PMP film; as a consequence, the film bends and the rotational speed changes by about 20 Hz. This kind of contactless long-distance interaction is an ideal platform for the development and study of many electro-optics devices in microgravity and low-friction conditions. In particular, we believe that this technology could find applications in research fields such as 3D dynamic displays and aerospace applications.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/310370

Flexible, Stretchable, Tunable, and Switchable DFB Laser
PHOTONICS
Autore/i: Lucchetta, Daniele Eugenio; Di Donato, Andrea; Francescangeli, Oriano; Riminesi, Cristiano; Singh, Gautam; Castagna, Riccardo
Classificazione: 1 Contributo su Rivista
Abstract: We are reporting on easily-made, flexible, wearable, and stretchable holographic gratings for tunable distributed-feedback lasers. The laser device is formed by the integration of a reflection volume phase grating in a flexible substrate. The grating is recorded in a photopolymerizable mixture by using optical holography. The photopolymerizing material is a new compound derived from a recently developed mixture which is based largely on haloalkanes and acrylates. An appropriate choice of photoinitiators promotes the photoactivation of the monomers at the writing wavelength of 460 nm. The laser device has a low emission threshold due to the high efficiency of the photopolymerization process at 460 nm. Finally, the amplified spontaneous emission of the device can be continuously tuned by simply bending the film. This peculiarity is promising for the manufacturing of optical pumped tunable organic lasers and flexible displays.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/310369

On the Asymmetry in Photo-Induced Motion of Graphene-Oxide Paper
COATINGS
Autore/i: Castagna, R.; Riminesi, C.; Di Donato, A.; Castaldo, R.; Avolio, R.; Montalto, L.; Vita, F.; Francescangeli, O.; Lucchetta, D. E.
Classificazione: 1 Contributo su Rivista
Abstract: We report on the photo-mobility properties of a free standing large area graphene oxide (GO) paper (GOP). The thickness of the film is ≈20 (Formula presented.) m. GOP is made by drop casting an aqueous suspension of GO on a microscope glass slide placed on a hot plate kept at the temperature of 70 °C. The film is peeled-off from the glass substrate and irradiated under different coherent and incoherent light sources. The film bends up to ≈55° when the irradiation is made using a near infra-red (NIR) incoherent incandescent lamp and returns back to the initial position when the NIR lamp is switched-off. The bending mechanism is attributed to the asymmetry of the GOP film obtained during the film formation process. We characterize the film morphology and structure using a Scanning Electron Microscopy (SEM) imaging and X-ray Diffraction (XRD) measurements, respectively. Remarkable differences between the two surfaces of the GOP are evidenced, both on a macroscopic length scale (surface roughness) and on a microscopic one (GO interlayer distance). This asymmetry results in different (negative) thermal expansion coefficients for the two film surfaces and hence in the bending of the film when the film temperature is increased by light absorption.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/324531

Light controlled bending of a holographic transmission phase grating
SMART MATERIALS AND STRUCTURES
Autore/i: Castagna, R.; Di Donato, A.; Strangi, G.; Eugenio Lucchetta, D.
Classificazione: 1 Contributo su Rivista
Abstract: We recorded a permanent phase transmission grating on a thin film made by using a recently developed holographic photomobile mixture. The recorded grating pitch falls in the visible range and can be optically manipulated by using an external coherent or incoherent low power light source. When the external light source illuminates the grating the entire structure bends and, as a consequence, the optical properties of the grating change. This peculiarity makes it possible to use the recorded periodic structure as an all-optically controlled free standing thin colour selector or light switch depending on the source used to illuminate the grating itself. Additionally, it could open up new possibilities for stretchable and reconfigurable holograms controlled by light as well as thin devices for optically reconfigurable dynamic communications and displays.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/296652

Top-Performance Transmission Gratings with Haloalkanes-Based Polymeric Composite Materials
MATERIALS
Autore/i: Castagna, R.; Riminesi, C.; Di Donato, A.; Francescangeli, O.; Lucchetta, D. E.
Classificazione: 1 Contributo su Rivista
Abstract: We report on highly transparent holographic phase transmission volume gratings recorded in the visible region at (Formula presented.) = 532 nm. The maximum measured diffraction efficiency is higher than 80% with a grating pitch of (Formula presented.) ≈ 300 nm and a refractive index modulation (Formula presented.) n ≈ 0.018. To obtain these results, we used a holographic mixture based on multi-reticulated acrylate and haloalkanes (1-bromo-butane and 1-bromo-hexane) and a synergic combination of camphore-quinone, which has a maximum absorbance at c.a. 470 nm, and R6G, here used as co-initiator, to efficiently initiate the photo-polymerization process. High transparent and high efficient holographic structures based on polymers can find applications in many research fields including integrated optics, sensors, high density data storage and security.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/309262

Experimental acoustic modal analysis of a tenor saxophone
THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA
Autore/i: Lucchetta, De; Schiaroli, L; Battista, G; Martarelli, M; Castellini, P
Classificazione: 1 Contributo su Rivista
Abstract: This paper presents an application of the Experimental Acoustic Modal Analysis (AMA) on a vintage 10 M Conn tenor saxophone. This technique originates from the traditional Modal Analysis which is commonly adopted to determine the dynamic behaviour of solid structures. The methodology is based on the measurement of Frequency Response Functions (FRFs) as a ratio of the acoustic pressure, measured by means of a set of microphones positioned along the saxophone body, and the volume velocity produced by an acoustic source and measured at the instrument input. The microphones are housed on the stripped saxophone keys by means of tailored three-dimensional printed adapters. The AMA makes use of the FRFs to extract modal parameters, such as resonance frequencies, loss factors, and mode shapes. These parameters pertain to the cavity modes of the saxophone passive resonator. The analysis has been performed for three different notes (B thorn , B, and C) and for two registers of the instrument in order to show the potential of the technique. Moreover, the influence of the mouthpiece volume on the cavity modes has been shown. The information obtained by AMA can find useful application in the validation of analytical or numerical models of this kind of musical instruments. (C) 2022 Acoustical Society of America.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/308342

Light-Controlled Direction of Distributed Feedback Laser Emission by Photo-Mobile Polymer Films
NANOMATERIALS
Autore/i: Lucchetta, De; Di Donato, A; Francescangeli, O; Singh, G; Castagna, R
Classificazione: 1 Contributo su Rivista
Abstract: We report on the realization of Distributed Feedback (DFB) lasing by a high-resolution reflection grating integrated in a Photomobile Polymer (PMP) film. The grating is recorded in a recently developed holographic mixture basically containing halolakanes/acrylates and a fluorescent dye molecule (Rhodamine 6G). The PMP-mixture is placed around the grating spot and a subsequent curing/photo-polymerization process is promoted by UV-irradiation. Such a process brings to the simultaneous formation of the PMP-film and the covalent link of the PMP-film to the DFB-grating area (PMP-DFB system). The PMP-DFB allows lasing action when optically pumped with a nano-pulsed green laser source. Moreover, under a low-power light-irradiation the PMP-DFB bends inducing a spatial readdressing of the DFB-laser emission. This device is the first example of a light-controlled direction of a DFB laser emission. It could represent a novel disruptive optical technology in many fields of Science, making feasible the approach to free standing and light-controllable lasers.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/306063

Scotch-Tape and Graphene-Oxide Photomobile Polymer Film
PHOTONICS
Autore/i: Castagna, R; Di Donato, A; Castaldo, R; Avolio, R; Francescangeli, O; Lucchetta, De
Classificazione: 1 Contributo su Rivista
Abstract: In this work, we report on the fabrication and photonic activation of a novel kind of photomobile polymer (PMP) film based mainly on a double layered asymmetric configuration. The PMP is cheap and extremely easy to make. It is made of PVC/isoprene tape with a layer of graphene-oxide (GO) attached. Under illumination at different intensities, and with coherent and incoherent light sources, the bending of the PMP film changes considerably. In particular, we noticed a more efficient bending effect when the film is directly exposed to high light intensities or to NIR radiation in the case of incoherent light sources. For the exposure times used in our experiments, the process is completely reversible when the light source is switched off. Additionally, if we paint the side of the PVC tape exposed to light black, the film is not able to return to its starting position and the bending results are permanent. This suggests that the presence of the GO-layer is responsible for the restoration of the position of the PMP film.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/306901

Lasing in Haloalkanes-based polymeric mixtures
OPTICAL MATERIALS
Autore/i: Lucchetta, D. E.; Di Donato, A.; Singh, G.; Castagna, R.
Classificazione: 1 Contributo su Rivista
Abstract: We report on lasing from a new organic mixture, in which a high resolution one dimensional reflection hologram is recorded via blue laser light irradiation at λ = 457.9 nm. The mixture is made by a photo-sensitized acrylate (di-pentaerythrithol-penta/hexa-acrylate) blended with halo-alkanes (1-bromo-hexane and 1-bromo-butane).The halo-alkanes mixture is selected on the basis of its ability to originate phase-separation from the acrylate during the photo-polymerization process and for its relatively low refractive index value. This last property allows the achievement of a good dielectric contrast between polymer-rich and haloalkane-rich layers constituting a one dimensional grating. The recorded structures show a narrow reflection peak and a 40% value diffraction efficiency. The addition of a small percentage (10−3 M) of a fluorescent molecule (9-[2-(Ethoxycarbonyl)phenyl]-N-ethyl-6-(ethylamino)-2,7-dimethyl-3H-xanthen-3-iminium chloride) allows lasing when the structure is optically pumped with a pulsed laser. The reflected grating peak (λr = 563 nm) is indeeed tuned to fall inside the emission band of the fluorescent molecule. The periodic grating selects and amplifies only a very narrow band of frequencies which represent our laser radiation.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/304879

Polymer-Based High Diffraction Efficiency and High Resolution Volume Holographic Transmission Gratings
CHEMOSENSORS
Autore/i: Castagna, Riccardo; Di Donato, Andrea; Francescangeli, Oriano; Lucchetta, Daniele Eugenio
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/306064

Light-Induced Dynamic Holography
MICROMACHINES
Autore/i: Lucchetta, D. E.; Di Donato, A.; Paturzo, M.; Singh, G.; Castagna, R.
Classificazione: 1 Contributo su Rivista
Abstract: Holographic photomobile polymers (H-PMP) are a novel class of photomobile materials in which holograms can be optically recorded. They can be used in a large variety of applications, including optical switches and color selectors. In this work, we show one of the most important properties of the photomobile film, which is the photophobicity of the unpolymerized parts of the photomobile mixture. In order to investigate this property, we recorded a transmission phase grating on an H-PMP film, and used a different experimental technique to measure the diffraction efficiency, surface tension, and mixture properties. The results allowed for a better understanding of the mechanism of the light-controlled bending observed in these compounds.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/296653

Optically Tunable Diffraction Efficiency in Reflection Grating Written in Photomobile Polymers
PHOTONICS
Autore/i: Castagna, Riccardo; Di Donato, Andrea; Francescangeli, Oriano; Lucchetta, Daniele Eugenio
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/307781

HKUST-1-Doped High-Resolution Volume Holographic Gratings
CHEMOSENSORS
Autore/i: Castagna, R; Tombesi, A; Riminesi, C; Di Donato, A; Francescangeli, O; Lucchetta, De
Classificazione: 1 Contributo su Rivista
Abstract: We report on transmission holographic gratings doped with metal organic frameworks (MOFs). As a first attempt, we focused on MOF-199, also known as HKUST-1, which is an efficient adsorbent of VOCs. HKUST-1 is not soluble in the pre-polymerized holographic mixture. For this reason, samples containing HKUST-1 show high light scattering. In this work, the recording of HKUST-1-doped one-dimensional transmission phase gratings is demonstrated. The optical properties of the recorded structures, such as diffraction efficiency and average refractive index changes, are reported by using angular analysis measurements. A first attempt to demonstrate the possibility of using the doped gratings as sensors is also reported.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/306062

Shape-driven optofluidic rotational actuation
THE EUROPEAN PHYSICAL JOURNAL PLUS
Autore/i: Lucchetta, D. E.; Simoni, F.; Sheremet, N.; Reshetnyak, V.; Castagna, R.
Classificazione: 1 Contributo su Rivista
Abstract: In the present work, we report light-induced rotation of millimeter-sized objects driven by their non-symmetric shape. The light-induced torque is originated by the thermal gradient on different sides of the teeth of star-shaped objects floating on liquid surfaces that leads to unbalanced surface tension due to the Marangoni effect. The dependence of the angular rotation on the number of teeth is demonstrated. The angular velocity is linearly dependent on the light intensity and follows a simple time behavior typical of objects moving under fluid friction. Graphic abstract: [Figure not available: see fulltext.]
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/293241

Spectral, morphological and dynamical analysis of a holographic grating recorded in a photo-mobile composite polymer mixture
NANOMATERIALS
Autore/i: Lucchetta, D. E.; Castagna, R.; Singh, G.; Riminesi, C.; Di Donato, A.
Classificazione: 1 Contributo su Rivista
Abstract: We report on the morphological, spectral and dynamical characterization of one-dimensional transmission holographic volume phase gratings, whose refractive index contrast and nanometric pitch are dynamically controlled by an incident laser light. The grating is obtained by the photo-polymerization of a recently developed photo-mobile holographic composite polymer material. The observed changes in the refractive index contrast and grating pitch strongly suggest that the reversible all-optical real-time modulation of the obtained diffraction efficiency is induced by nano-fluidics.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/293244

Optically tunable diffraction efficiency by photo-mobile holographic composite polymer material
OPTICAL MATERIALS
Autore/i: Lucchetta, D. E.; Di Donato, A.; Singh, G.; Tombesi, A.; Castagna, R.
Classificazione: 1 Contributo su Rivista
Abstract: We report on the fabrication and optical characterization of one-dimensional transmission holographic volume phase gratings written on a novel holographic composite mixture. The mixture is derived from a recently developed photo-mobile polymeric composite material. The transmission gratings recorded on the photo-mobile film are constituted by polymeric walls and low viscous inter-walls material. Using an external pumping laser operating at λ = 457.9 nm the transmission efficiency linearly increases with the laser power and, in our range of power values, the phenomenon is completely reversible. At highest power level a 30% diffraction efficiency is achieved. The increase of the diffraction efficiency is related to the increase of the refractive index contrast of the grating mixture. In particular, under illumination, the low viscous material escapes from the irradiated area. This feature could explain the experimentally observed changes of the refractive index contrast.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/293242

Near-frequency photons Y-splitter
APPLIED MATERIALS TODAY
Autore/i: Castagna, R.; Lucchetta, D. E.; Rippa, M.; Xu, J. -H.; Di Donato, A.
Classificazione: 1 Contributo su Rivista
Abstract: We are reporting on a wavelength-controlled anomalous angular light scattering with a very high spatial angular dispersion in correspondence to a very small frequencies range. Essentially, we present a device able to Y-split in-air wavelengths of a laser beam few tens of nanometers away from each other. We explain its working mechanism through Moirè-interactions between structured-light and all-dielectric matter structured by light. More precisely, we ascribe this effect to Moiré-beats between holographic patterns recorded in a material and a spatially modulated wave-front of a probe-beam with slightly different spatial frequency content.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/277841

Physics of matter: from the nanoscale structure to the macroscopic properties of materials
The First outstanding 50 years of "Università Politecnica delle Marche"
Autore/i: Albertini, G.; Barucca, G.; Francescangeli, O.; Lucchetta, D. E.; Lucchetti, L.; Mengucci, P.; Rinaldi, D.; Simoni, F.; Vita, F.
Editore: Springer
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/275117

Light-actuated contactless macro motors exploiting Bénard–Marangoni convection
OPTICS EXPRESS
Autore/i: Lucchetta, D. E.; Castagna, R.; Simoni, F.
Classificazione: 1 Contributo su Rivista
Abstract: Near-infrared light is commonly used to move small objects floating on water by exploiting the Bénard-Marangoni convection. This is because infrared light is absorbed well by water and the induced thermal gradients are responsible for the objects’ motion. However, visible light was recently used to move macroscopic objects on the free liquid surfaces. In this work, we show the use of visible light to rotate symmetric millimeter-sized objects. Those objects represent light-driven macro motors that are able to work in a continuous or step-by-step mode. We studied light intensity’s effects on our system’s angular velocity and estimated the entire process’s conversion efficiency.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/277839

Lasing from chiral doped nematic liquid crystal droplets generated in a microfluidic device
MOLECULAR CRYSTALS AND LIQUID CRYSTALS
Autore/i: Lucchetta, D. E.; Simoni, F.; Hernandez, R. J.; Mazzulla, A.; Cipparrone, Gabriella
Classificazione: 1 Contributo su Rivista
Abstract: Microfluidics generated liquid crystal (LC) droplets are currently used as microresonators in optofluidics applications due to their small size, narrow droplets diameter distributions, high Q-factor and tunability properties. In this work we report a short review regarding lasing from cholesteric liquid crystals (CLCs) confined in spherical microdroplets generated in a thermally stabilized environment by using a microfluidic technique. The photonic bandgaps (PBGs) have been theoretically calculated and experimentally measured as a function of temperature. A wide tuning effect of hundreds of nanometers has been experimentally observed for the main PBG and reported for two different concentrations of the chiral dopant used to give chirality to the nematic LC. A single-droplet lasing effect has been reported and optimized by using a stop flow technique and the dynamic of the reorientation inside the droplets observed under a polarized optical microscope integrated into the experimental setup
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/258535

An Unconventional Approach to Photomobile Composite Polymer Films
ADVANCED MATERIALS
Autore/i: Castagna, Riccardo; Nucara, Luca; Simoni, Francesco; Greci, Lucedio; Rippa, Massimo; Petti, Lucia; Lucchetta, Daniele Eugenio
Classificazione: 1 Contributo su Rivista
Abstract: Photomobile polymer (Pmp) films are fabricated by using a cheap and fast process. The working mechanism of the Pmp-film motion under illumination is explained. Details concerning the film structure and formation are given. Two related applications regarding light-induced caterpillar-miming motion and photocontrolled electrical switches are proposed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/247650

Optical measurement of flow rate in a microfluidic channel
MICROFLUIDICS AND NANOFLUIDICS
Autore/i: Lucchetta, Daniele Eugenio; Vita, Francesco; Francescangeli, D.; Francescangeli, Oriano; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: A way to measure flow rate inside a microchannel using a contactless optical technique is reported. The optofluidic device consists of a Bragg grating written on a soft wall, namely a Mylar stripe glued on the top of a microfluidic channel. Diffraction of a white-light probe beam is used to detect the small displacements of the grating caused by the liquid flowing inside the microchannel. A simple model of the hydraulic circuit gives theoretical expressions for the response time of the diffracted signal allowing to fit the experimental data and determine the applied flow rates.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/230228

Structured beam diffraction
OPTICS LETTERS
Autore/i: Castagna, Riccardo; DI DONATO, Andrea; Nucara, L.; Xu, J. H.; Lucchetta, Daniele Eugenio; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: We report on the observation of a modulated pattern induced by a single laser beam in a polymeric film. In spite of the simple geometrical configuration, the analysis of the far field diffraction pattern allows a sensitive retrieving of the wavelength of the recording beam and of its incidence angle, pointing out the high information content of the recorded spot. A theoretical model is presented which satisfactorily explains the observed behavior. It takes into account the interaction of structured light with structured matter with the same symmetries and spatial modulation frequencies close to each other. This result shows a feature of the interaction between structured light and structured matter which has not been explored yet. © 2016 Optical Society of America.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/237738

Low threshold Fabry-Perot optofluidic resonator fabricated by femtosecond laser micromachining
OPTICS EXPRESS
Autore/i: Simoni, Francesco; Bonfadini, S.; Spegni, Paolo; Lo Turco, S.; Lucchetta, Daniele Eugenio; Criante, Luigino
Classificazione: 1 Contributo su Rivista
Abstract: We report the realization and characterization of an optofluidic microlaser based on a Fabry-Perot resonator fabricated by exploiting two direct writing fabrication techniques: the femtosecond laser micromachining and the inkjet printing technology. In this way a standard Fabry-Perot cavity has been integrated into an optofluidic chip. When using rhodamine 6G dissolved in ethanol at concentration of 5·10-3 mol/l, laser emission was detected at a threshold energy density of 1.8 μJ/mm2 at least one order of magnitude lower than state-of-the-art optofluidic lasers. Linewidth below ∼0.6 nm was measured under these conditions with a quality factor Q∼103. These performances and robustness of the device makes it an excellent candidate for biosensing, security and environment monitoring applications. ©2016 Optical Society of America.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/237736

Polymer stabilized Monodispersed Liquid Crystal Droplets: Microfluidics Generation and Optical Analysis
OPTICAL DATA PROCESSING AND STORAGE
Autore/i: Lucchetta, Daniele Eugenio; Simoni, Francesco; Pagliusi, P.; Cipparrone, G.
Classificazione: 1 Contributo su Rivista
Abstract: Liquid crystal droplets are widely used in optics and photonics applications. They can act as simple resonators or be arranged in interconnected periodic con- gurations when their external dimension are similar. In this work we optically analyze and describe the microuidic generation of liquid crystal droplets in a thermally stabilized environment, namely water, which enables a narrow droplets diameter distribution. We demonstrate a ne control of the droplet dimensions in both nematic and isotropic phases by controlling the ratio between liquid crystal and water ows. Droplets generated in the isotropic phase show a complex internal structure which reects their high degree of internal disorder. Moreover, the internal conguration of the droplets also depends on the purity degree of the water in which they grow. In order to investigate their size distribution and their internal structure, a small amount of photo-polymerizable agent (NOA61 optical glue) was added to the liquid crystal to stabilize the droplets structure and to avoid their coalescence. Acting this way, polymer stabilized liquid crystal droplets were created after light induced polymerization, which are stable even after water evaporation. The polarized microscope analysis shows that the bipolar or radial order of the liquid crystal is still preserved inside the droplets depending on the water purity. Moreover an improved size uniformity is reported.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/228826

Light moves macro-objects
Progress in Electromagnetics Research Symposium
Autore/i: Lucchetta, Daniele Eugenio; Simoni, Francesco; Nucara, L.; Castagna, Riccardo
Editore: Electromagnetics Academy
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Photons energy can be conventionally converted into mechanical work through a series of energy expensive steps. It has been shown how some of these steps can be bypassed obtaining a direct conversion of photons energy into mechanical work. The most common way consists of using light in the visible or near infrared to move small objects floating on fluid surfaces exploiting the Marangoni effect. In this work we use a low power visible light source to induce a thermal surface tension gradient thus moving a floating object on a fluid surface. By real time tracking of the object trajectory we can determine some physical properties related to the floating object and to the supporting fluid. Moreover from the experimental data fitting we can evaluate the applied driving force due to light irradiation and object heating. In addition we show how even transparent object can be moved by light when the supporting fluid is properly doped.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/230724

Controlled-motion of floating macro-objects induced by light
AIP ADVANCES
Autore/i: Lucchetta, Daniele Eugenio; Simoni, Francesco; Nucara, Luca; Castagna, Riccardo
Classificazione: 1 Contributo su Rivista
Abstract: Photons energy can be conventionally converted to mechanical work through a series of energy-expensive steps such as for example delivery and storage. However, these steps can be bypassed obtaining a straightforward conversion of photons energy to mechanical work. As an example, in literature, high power near infrared light is used to move small objects floating on fluid surfaces, exploiting the Marangoni effect. In this work we use a low power non-collimated visible laser-light to induce thermal surface tension gradients, resulting in the movement of objects floating on fluid surfaces. By real time tracking of the object trajectories, we evaluate the average applied driving force caused by the light irradiation. In addition we show how transparent objects can be moved by light when the supporting fluids are properly doped.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/228827

Hybrid surface-relief/volume one dimensional holographic gratings
OPTICAL MATERIALS
Autore/i: Lucchetta, Daniele Eugenio; Spegni, Paolo; DI DONATO, Andrea; Simoni, Francesco; Castagna, Riccardo
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/228766

Iron (III)/multiacrylate-based holographic mixtures
JOURNAL OF APPLIED PHYSICS
Autore/i: Lucchetta, Daniele Eugenio; L., Nucara; L., Criante; Simoni, Francesco; A., Boni; Ji Hua, Xu; R., Bizzarri; R., Castagna
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/160914

Laser light polarization plastic visualizer: light scattering distribution and anisotropy
RSC ADVANCES
Autore/i: A., Shalit; Lucchetta, Daniele Eugenio; L., Criante; Vita, Francesco; J. R., Tasseva; Simoni, Francesco; L., Franco; R., Bizzarri; P., Faraci; R., Conte; L., Viti; R., Kaner; R., Castagna
Classificazione: 1 Contributo su Rivista
Abstract: A laser light polarization visualizer (LPV) is obtainable by the photopolymerization of a multi-acrylate monomer, initiated by diketones under a single beam nano-pulsed (lambda = 532 nm) laser light. The derived light scattering distribution and polymer anisotropy are dependent on the polarization state of the incident-polymerizing beam. By adding a 1-haloalkane to the mixture, the solid angle of the scattered light increases. This phenomenon is dependent on the halogen of the haloalkane.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/160913

First-order optical Freedericksz transition in a dye-doped nematic liquid crystal
OPTICS LETTERS
Autore/i: Simoni, Francesco; 1, ; Lucchetta, Daniele Eugenio; Lucchetti, Liana; H. L., Ong; S. V., Serak; N., Tabiryan
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/106662

Laser emission based on first order reflection by novel compositepolymeric gratings
PHOTONICS AND NANOSTRUCTURES
Autore/i: Lucchetta, Daniele Eugenio; Vita, Francesco; Castagna, R.; Francescangeli, Oriano; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: We have recently developed a novel composite photosensitive material allowing the holographic recording of diffraction gratings with high diffraction efficiency, transparency and spatial resolution. In the present work such material was used to produce a low cost and easy to make optically pumped, organic distributed feedback laser, working on the first diffraction order of a high quality grating doped with a photoluminescent dye. The experimental geometry incorporates two optical fibers which can be used to characterize the laser device in any development stage, collect emitted laser radiation, and offer an alternative way to pump the grating structure. The material properties and the used geometry allow the achievement of good performances in terms of energy threshold and linewidth. A comparison with holographic gratings made with holographic-polymer dispersed liquid crystals is reported to highlight the key role of the developed material.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/66078

Polarization-dependent laser-light structured directionality with polymer composite materials
MATERIALS LETTERS
Autore/i: Shalit, A.; Lucchetta, Daniele Eugenio; Piazza, V.; Simoni, Francesco; Bizzarri, R.; Castagna, R.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/73662

Microfluidic transport of photopolymerizable species for laser source integration in lab-on-a-chip photonic devices
PHOTONICS AND NANOSTRUCTURES
Autore/i: Lucchetta, Daniele Eugenio; Castagna, R.; Vita, Francesco; Gianni, A.; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: We recently developed a novel composite photopolymerizable material which allows the holographic recording of diffraction gratings with optimal optical and mechanical properties (high diffraction efficiency, transparency and spatial resolution, low shrinkage, long time stability). This material was successfully used to produce a low cost and easy to make optically pumped, organic distributed feedback laser, working on the first diffraction order of a high quality Bragg grating doped with a photoluminescent dye. Here we show the possibility of positioning these micrometer sized light sources at any point of a generic lab-on-a-chip device by borrowing experimental techniques commonly used in the fields of microfluidics and optofluidics. In particular, a microfluidic channel has been imprinted by soft lithography in a polydimethylsiloxane substrate in order to convey the photopolymerizable mixture to a particular area of the sample, where the laser device has been holographically recorded. A characterization of the lasing properties of this device has been carried out. The proposed approach allows a better confinement of the emitted light and overcomes some physical constrains (resolution, aspect ratio) of PDMS based microfluidic laser thus opening new possibilities for the complex integration of organic laser sources in lab-on-a-chip devices.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/73665

Holographic polymeric materials for optical processing: Microlasers, data storage and all optical switching
Information Photonics (IP), 2011 ICO International Conference
Autore/i: Lucchetta, D. E.; Vita, F.; Castagna, R.; Criante, L.; Francescangeli, O.; Simoni, F.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: We report on recent research in the field of optical processing with microlasers, high density optical storage media and all-optical switching devices. By combining different materials and optical holography some devices which show attractive optical properties and interesting wide range of potential applications will be presented.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/66223

Microlasers based on holographic PDLC structures
Liquid Crystal Microlasers
Autore/i: Simoni, Francesco; Lucchetta, Daniele Eugenio; L., Criante; Francescangeli, Oriano; Vita, Francesco
Editore: Transword Research Network
Luogo di pubblicazione: TRIVANDRUM-695 023, KERALA
Classificazione: 2 Contributo in Volume
Abstract: Invited Article
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/41779

All-optical switching of diffraction gratings infiltrated with dye-doped liquid crystals
APPLIED PHYSICS LETTERS
Autore/i: Lucchetta, Daniele Eugenio; Vita, Francesco; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: We report the realization and the characterization of an all-optical switching device based on a transmission grating recorded in a polymeric substrate infiltrated with a methyl red-doped liquid crystal. The properties of this highly nonlinear mixture are exploited to modulate the diffraction of the grating by a pump beam when a static electric field is applied. The behavior of the device is in agreement with the existing model for methyl red-doped liquid crystals. (C) 2010 American Institute of Physics.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/54138

Distributed feedback all-organic microlaser based on holographic polymer dispersed liquid crystals
APPLIED PHYSICS LETTERS
Autore/i: Criante, L.; Lucchetta, D. E.; Vita, F.; Castagna, R.; Simoni, F.
Classificazione: 1 Contributo su Rivista
Abstract: An optically pumped vertically emitting all-organic laser, based on a holographic polymer dispersed liquid crystal reflection grating operating in a distributed feedback configuration, is presented. The used experimental geometry overcomes the main drawbacks characterizing similar systems, allowing virtually infinite operations and absence of damages associated with the high energy of the optical pumping.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51049

Nanocomposite polymeric materials for high density optical storage
JOURNAL OF OPTICS. A, PURE AND APPLIED OPTICS
Autore/i: Criante, Luigino; Castagna, Riccardo; Vita, Francesco; Lucchetta, Daniele Eugenio; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: We report the results of an extended investigation performed on composite polymeric materials with the aim of obtaining compounds suitable for holographic recording. In order to investigate the material properties a characterization of holographic reflection gratings at different writing wavelength (514.5, 457 and 405 nm) has been performed. The volume grating presents high diffraction efficiency (>60%), high sensitivity (>10(3) cm J(-1)) and refractive index modulation Delta n approximate to 0.01 even for writing wavelength in the blue range. We show that following a strategy of two basic components leading to phase separation during the photopolymerization process, most of the requirements for holographic data storage are achieved. The one that needs further improvement concerns long term mechanical stability.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/52902

Superior perfomance Composite Materials for High-Density Optical Data Storage
ADVANCED MATERIALS
Autore/i: Castagna, R; Vita, Francesco; Lucchetta, Daniele Eugenio; Criante, L; Simoni, Francesco
Editore: Wiley-VCH Verlag GmBH:PO Box 101161, D 69451 Weinheim Germany:011 49 6201 606147, EMAIL: service@wiley-vch.de, INTERNET: http://www.wiley-vch.de, Fax: 011 49 6201 606328
Classificazione: 1 Contributo su Rivista
Abstract: High-resolution holographic gratings are obtained using a combination of a multifunctional acrylate (DPHP/HA), a low-molecular-weight glass-forming liquid epoxy-aromatic resin (TPMTGE), and a UV-photoinitiator (Irgacure 819). Their optical properties (sensitivity, transparency, and optical shrinkage) are promising for high-density optical data storage applications.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/27695

Effects of resin addition on Holographic Polymer Dispersed Liquid Crystals
JOURNAL OF OPTICS. A, PURE AND APPLIED OPTICS
Autore/i: Vita, Francesco; Lucchetta, Daniele Eugenio; Castagna, Riccardo; Criante, Luigino; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: The effects of epoxy resin addition to a standard acrylate-based holographic polymer dispersed liquid-crystal mixture are investigated. Different resin concentrations are used and we show how the presence of the resin results in transmission gratings characterized by negligible scattering, polarization independent behaviour and lower switching voltages. These experimental results are explained by means of morphological scanning electron microscopy analyses.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/52224

Superior perfomance Composite Materials for High-Density Optical Data Storage
ADVANCED MATERIALS
Autore/i: R., Castagna; Vita, Francesco; Lucchetta, Daniele Eugenio; L., Criante; Simoni, Francesco
Editore: Composites Worldwide Incorporated:991C Lomas Santa Fe Drive, PMB469:Solana Beach, CA 92075:(858)755-1372, EMAIL: info@compositesnews.com, INTERNET: http://www.compositesnews.com, Fax: (858)755-5271
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/36386

Haloalkane-based polymeric mixture for high density optical data storage
APPLIED PHYSICS LETTERS
Autore/i: R., Castagna; Vita, Francesco; Lucchetta, Daniele Eugenio; L., Criante; L., Greci; Simoni, Francesco
Editore: American Institute of Physics:2 Huntington Quadrangle, Suite 1NO1:Melville, NY 11747:(800)344-6902, (631)576-2287, EMAIL: subs@aip.org, INTERNET: http://www.aip.org, Fax: (516)349-9704
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/36389

At a glance determination of laser ligth polarization state
APPLIED PHYSICS LETTERS
Autore/i: Castagna, R.; Lucchetta, Daniele Eugenio; Vita, Francesco; Criante, L.; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: We report a simple technique for the visual determination of a laser light polarization state. The technique is based on a phenomenon occurring when laser light impinges on a particular photopolymerizable mixture sandwiched between two glass plates. After a brief irradiation, some polarization dependent patterns are observed far from the incidence spot. This effect is due to light scattered by the polymerized material and waveguided by the glass. A visual inspection of the characteristic patterns allows an immediate determination of the light polarization. This technique could be conveniently exploited for qualitative and/or quantitative polarimetry, as well as for designing polarization-driven devices.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/50265

Method and apparatus for measuring the refractive index of a material with Bragg gratings
Autore/i: Simoni, Francesco; Castagna, R.; Criante, L.; Lucchetta, Daniele Eugenio; Vita, Francesco
Classificazione: 6 Brevetti
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/58231

Haloalkane-based polymeric mixture for high density optical data storage
OPTICAL MATERIALS
Autore/i: Castagna, R; Vita, Francesco; Lucchetta, Daniele Eugenio; Criante, L; Greci, L; Simoni, Francesco
Editore: Elsevier BV:PO Box 211, 1000 AE Amsterdam Netherlands:011 31 20 4853757, 011 31 20 4853642, 011 31 20 4853641, EMAIL: nlinfo-f@elsevier.nl, INTERNET: http://www.elsevier.nl, Fax: 011 31 20 4853598
Classificazione: 1 Contributo su Rivista
Abstract: We present an investigation oil new organic mixtures for high resolution holographic data recording. Reflection holograms were obtained via blue laser light irradiation (lambda = 457.9 nm) on photo-sensitive acrylate and 1-chloro-hexane or 1-bromo-hexane based mixtures. These haloalkanes were selected oil the basis of their ability to originate phase separation from acrylate during the photo-polymerization process and for their lower refractive index with respect to the used poly-acrylate monomer. This last property allowed the achievement of a good dielectric contrast between polymer and haloalkane-rich layers. The recorded holograms have been investigated and optically characterized focusing on holographic data storage requirements. Finally, the results were compared with those concerning holographic polymer dispersed liquid crystal, already proposed for optical data storage applications.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/27689

Holographic patterning of composite polymeric materials for photonic applications
MOLECULAR CRYSTALS AND LIQUID CRYSTALS
Autore/i: Criante, L; Castagna, R; Vita, Francesco; Lucchetta, Daniele Eugenio; Gobbi, Luigi; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: We report the results of an extended investigation on holographic patterning of novel liquid crystal-polymer materials, developed with the aim of producing one- and two-dimensional periodic structures to be used in optical devices for data storage and processing. Characterization of reflection gratings recorded at 405 rim resulted in values of diffraction efficiency (> 60%), sensitivity (Up to 10(4) cm/J) and refractive index modulation (Delta n similar to 0.01) that make these materials interesting for optical storage applications. Large-area two-dimensional periodic structures have been also patterned using a multibeam photolitigraphic technique. These planar photonic crystals have many possible uses, both in fundamental and applied physics.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51376

Novel blue sensitive polymeric materials for optical data storage
Organic 3D Photonics Materials and Devices II
Autore/i: R., Castagna; L., Criante; Vita, Francesco; Lucchetta, Daniele Eugenio; S., Frohmann; T., Feid; S., Orlic; Simoni, Francesco
Editore: SPIE / International Society for Optical Engineering:PO Box 10:Bellingham, WA 98227:(360)676-3290, EMAIL: spie@spie.org, INTERNET: http://www.spie.org, Fax: (360)647-1445
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: We report the properties of a new polymer-guest photosensitive mixture based on two monomers with different properties as basic components. The material has been characterized by recording holographic gratings using a low power blue laser (405 nm) and a spectro-photometric technique to get the optical properties of the grating during and after recording. The detected grating shows a very high sensitivity (of the order of 10^3 cm/J) and a surprising "antishrinkage" phenomenon (red-shift of the Bragg reflection grating wavelength).
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/36385

Rifrattometro spettrofotometrico
Autore/i: Simoni, Francesco; Castagna, R; Criante, L; Lucchetta, Daniele Eugenio; Vita, Francesco
Classificazione: 6 Brevetti
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/53623

Composizione di miscele organiche sensibili al blu usabili per l'immagazzinamento olografico dell'informazione
Autore/i: Simoni, Francesco; Castagna, R; Criante, L; Lucchetta, Daniele Eugenio; Vita, Francesco
Classificazione: 6 Brevetti
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/53641

Detailed investigation of high-resolution reflection gratings through angular-selectivity measurements
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. B, OPTICAL PHYSICS
Autore/i: Vita, Francesco; Lucchetta, Daniele Eugenio; Castagna, R.; Francescangeli, Oriano; Criante, L.; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: We performed an investigation on Bragg reflection gratings recorded in blue-sensitive holographic polymer dispersed liquid crystals. The use of a position-sensitive detector allows selective measurements of the reflected light, never before reported in these materials, to our knowledge. We can show that by using this experimental technique it is possible to detect the formation of multiple gratings, even when the transmission spectrum does not show multiple peaks. The results are discussed in the frame of existing coupled-wave theory for anisotropic materials, allowing us to obtain the optical characterization of the gratings.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/50214

Polymeric composite materials for optical data storage and processing
2007 DIGEST OF THE LEOS SUMMER TOPICAL MEETINGS
Autore/i: Simoni, Francesco; Castagna, R.; Criante, L.; Francescangeli, Oriano; Lucchetta, Daniele Eugenio; Vita, Francesco
Editore: IEEE / Institute of Electrical and Electronics Engineers Incorporated:445 Hoes Lane:Piscataway, NJ 08854:(800)701-4333, (732)981-0060, EMAIL: subscription-service@ieee.org, INTERNET: http://www.ieee.org, Fax: (732)981-9667
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/81893

Light-polarization visualizer with polymeric composite mixtures
Optics InfoBase Conference Papers
Autore/i: Castagna, Riccardo; Lucchetta, Daniele Eugenio; Criante, Luigino; Vita, Francesco; Simoni, Francesco
Editore: Optical Society of America
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/241397

Blue sensitive mixtures for holographic optical data storage
Optics InfoBase Conference Papers
Autore/i: Castagna, Riccardo; Criante, Luigino; Lucchetta, Daniele Eugenio; Vita, Francesco; Simoni, Francesco
Editore: Optical Society of America
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/241399

Realization and characterization of organic two-dimensional periodic structures
Optics InfoBase Conference Papers
Autore/i: Vita, Francesco; Lucchetta, Daniele Eugenio; Castagna, Riccardo; Criante, Luigino; Francescangeli, Oriano; Pierantoni, Luca; Simoni, Francesco
Editore: Optical Society of American (OSA)
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/241400

High resolution optical data storage in composite polymeric blue sensitive materials
CLEO/Europe and IQEC 2007 Conference Digest
Autore/i: Criante, Luigino; Vita, Francesco; Castagna, Riccardo; Lucchetta, Daniele Eugenio; Simoni, Francesco
Editore: Optical Society of America
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/240969

New composite blue sensitive materials for high resolution optical data storage
Proceedings Volume 6657, Organic 3D Photonics Materials and Devices; 665704 (2007)
Autore/i: L., Criante; Vita, Francesco; R., Castagna; Lucchetta, Daniele Eugenio; Simoni, Francesco; S., Frohmann; T., Feid; S., Orlic
Editore: Proceedings of SPIE - The International Society for Optical Engineering
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/36308

Nitroxide radicals reduce shrinkage in acrylate-based holographic gratings
OPTICAL MATERIALS
Autore/i: R., Castagna; Vita, Francesco; Lucchetta, Daniele Eugenio; L., Criante; Greci, Lucedio; P., Ferraris; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: High resolution holographic polymer dispersed liquid crystal gratings are photo-induced periodic structures commonly affected by shrinkage. This phenomenon represents a problem in several application fields such as in high density optical storage. In this work we observed that, by directly monitoring the blue-shift of the reflection peak of the periodic structure, an evident shrinkage reduction occurs using the nitroxide radical Tinuvin770-N-yloxy [(bis(2,2,6,6-tetramethyl-piperidine-1-yloxy-4-yl)-sebacate] as inhibitor of polymerization. This compound is a stable hindered amine light stabilizer-derived free radical, which plays a significant role in the photopolymerization dynamics.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/53422

Optical proprties of organic-based periodic structures
LIQUID CRYSTALS XI
Autore/i: Lucchetta, Daniele Eugenio; Vita, Francesco; R., Castagna; Francescangeli, Oriano; Simoni, Francesco
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Invited Paper
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/47219

Characterization of blue sensitive holographic polymer dispersed liquid crystal for microholographic data storage
MOLECULAR CRYSTALS AND LIQUID CRYSTALS
Autore/i: Criante, L; Vita, Francesco; Castagna, R; Lucchetta, Daniele Eugenio; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: We present the results of an extended investigation performed on holographic reflection gratings recorded in blue sensitive polymer dispersed liquid crystals in view of a possible application in optical data-storage. The analysis has been performed by means of real-time spectroscopy during the polymerization process. The analysis of transmission spectra during the recording process showed a fast photopolymerization, resulting in the rapid formation of a reflection peak. Gratings characterized by high spatial frequency (> 7000 lines/mm), high diffraction efficiency (up to 50%) and large refractive index modulation (Delta n similar to 0.008) have been obtained. Unfortunately, the monomer conversion into a polymer network is generally characterized by a strong packing, with a consequent reduction in volume (polymerization shrinkage). This phenomenon induces a significant blue-shift of the reflected wavelength. With the aim of better understanding and possibly reducing the shrinkage, a new high-sensitive experimental technique has been developed to measure shrinkage effects in multi-component polymeric mixtures.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/53114

New composite blue sensitive materials for high resolution optical data storage
Organic 3D Photonics Materials and Devices
Autore/i: L., Criante; Vita, Francesco; R., Castagna; Lucchetta, Daniele Eugenio; Simoni, Francesco; S., Frohmann; T., Feid; S., Orlic
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: In the last three decades several kinds of organic mixtures for holographic recording were developed in order to achieve a new class of DVD-like optical memories for high-density optical data storage. The holographic materials should satisfy the following requirements: high sensitivity to blue light, low losses, high spatial resolution and long term stability. To this aim we developed new organic photosensitive mixtures based on only three components. We recorded high spatial frequency reflection gratings up to 7400 lines/mm with blue laser light (405 nm) by using a conventional holographic setup. We obtained a macro grating diffraction efficiency up to 67%, refractive index modulation over 0.01, optical shrinkage < 2 % and overall losses similar to 5%. In order to characterize data-storage materials independently on the experimental conditions, the sensitivity has been evaluated through the S parameter which takes into account the diffraction efficiency, recording light intensity, exposure time and sample thickness. The amazing obtained values of S >10^5 cm/J evidences a very fast recording process with a very low writing intensity (less than 20 MW/cm^2) corresponding to a recording energy density of few mJ/cm^2. The performance of these materials have been also tested in the micro-holographic geometry.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/72422

Optical properties of organic-based periodic structures
Liquid Crystals XI
Autore/i: Lucchetta, Daniele Eugenio; Vita, Francesco; Castagna, R.; Francescangeli, Oriano; Simoni, Francesco
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/72421

Optical properties of organic-based periodic structures
Holography 2005: International Conference on Holography, Optical Recording, and Processing of Information
Autore/i: Lucchetta, Daniele Eugenio; Vita, Francesco; R., Castagna; Francescangeli, Oriano; Simoni, Francesco
Editore: SPIE / International Society for Optical Engineering:PO Box 10:Bellingham, WA 98227:(360)676-3290, EMAIL: spie@spie.org, INTERNET: http://www.spie.org, Fax: (360)647-1445
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The aim of this work is to understand the effects of the shrinkage phenomenon in H-PDLC reflection gratings trough the real time analysis of their transmission spectra during the recording process. The real time spectroscopic analysis of the samples showed a light intensity dependent free-radical polymerization indicated by a quick growth of the reflection peak whose corresponding diffraction efficiency, measured at normal incidence, is in the range 40%-45% depending on the photopolymerization conditions. An optical shrinkage corresponding to a 4.3% displacement of the reflected wavelength from the expected value has been detected. This value of the shrinkage is in agreement to that mesaured in similar system.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/36307

Large-area photonic structures in free-standing films
APPLIED PHYSICS LETTERS
Autore/i: Vita, Francesco; Lucchetta, Daniele Eugenio; Castagna, R; Criante, L; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: The authors report the fabrication of freestanding two-dimensional photonic crystals in organic materials. Large-area patterned structures, with submicrometric spatial resolution, have been recorded in spin-coated polymer-dispersed liquid crystals via holographic photolithography. After the removal of the liquid crystal, the polymeric film is peeled off from the substrate. Scanning electron microscope images show the high homogeneity of the structure in any spatial direction. These films can be conveniently used in a wide range of applications, from templates for high-refractive index photonic crystals to flexible photonic elements.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/52100

Recording of evanescent waves in holographic polymer dispersed liquid crystals
JOURNAL OF OPTICS. A, PURE AND APPLIED OPTICS
Autore/i: K., Beev; L., Criante; Lucchetta, Daniele Eugenio; Simoni, Francesco; S., Sainov
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51798

Total internal reflection holographic gratings recorded in polymer-dispersed liquid crystals
OPTICS COMMUNICATIONS
Autore/i: K., Beev; L., Criante; Lucchetta, Daniele Eugenio; Simoni, Francesco; S., Sainov
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51160

Characterization of Nano-PDLC as optical data storage materials
MOLECULAR CRYSTALS AND LIQUID CRYSTALS
Autore/i: Criante, L; Lucchetta, Daniele Eugenio; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51797

New holographic gratings recorded in polymer-dispersed liquid crystals
Holography 2005: International Conference on Holography, Optical Recording, and Processing of Information
Autore/i: K., Beev; L., Criante; Lucchetta, Daniele Eugenio; Simoni, Francesco; S., Sainov
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/72423

Spectral analysis of shrinkage in holographic material suitable for optical storage applications
Holography 2005: International Conference on Holography, Optical Recording, and Processing of Information
Autore/i: L., Criante; K., Beev; Lucchetta, Daniele Eugenio; Simoni, Francesco
Editore: SPIE / International Society for Optical Engineering:PO Box 10:Bellingham, WA 98227:(360)676-3290, EMAIL: spie@spie.org, INTERNET: http://www.spie.org, Fax: (360)647-1445
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/36464

Spectral analysis of shrinkage in holographic materials suitable for optical storage applications
Holography 2005: International Conference on Holography, Optical Recording, and Processing of Information
Autore/i: L., Criante; K., Beev; Lucchetta, Daniele Eugenio; Simoni, Francesco
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/72424

High resolution optical data storage in composite polymeric materials
Optics InfoBase Conference Papers
Autore/i: Criante, L.; Vita, Francesco; Castagna, R.; Lucchetta, Daniele Eugenio; Simoni, Francesco
Editore: Optical Society of America
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: High resolution reflection gratings have been recorded at 457 nm in polymer composites. They exhibited high diffraction efficiency and sensitivity, low losses, and index modulation over 0.01. Finally recording of micro-gratings has been carried out.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/228975

Optical and mechanical shrinkage effects in dye-doped photonic bandgap structures based on organic materials
PHYSICAL REVIEW E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS
Autore/i: Lucchetta, Daniele Eugenio; Francescangeli, Oriano; Criante, Luigino; Simoni, Francesco; Pierantoni, Luca; Rozzi, Tullio; Scoponi, M.; Rossetti, S.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/50093

New holographic gratings recorded in polymer-dispersed liquid crystals
PROCEEDINGS OF SPIE, THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING
Autore/i: K., Beev; L., Criante; Lucchetta, Daniele Eugenio; Simoni, Francesco; S., Sainov
Editore: SPIE / International Society for Optical Engineering:PO Box 10:Bellingham, WA 98227:(360)676-3290, EMAIL: spie@spie.org, INTERNET: http://www.spie.org, Fax: (360)647-1445
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/36393

Characterization of polymeric materials for microholographic data storage
Organic Holographic Materials and Applications III
Autore/i: L., Criante; K., Beev; Lucchetta, Daniele Eugenio; Simoni, Francesco; S., Frohmann; S., Orlic; Proceedings of, Spie; 5939, 61
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/72425

Compact lasers based on H-PDLC gratings”, Molecular Crystals Liquid Crystals
MOLECULAR CRYSTALS AND LIQUID CRYSTALS
Autore/i: Lucchetta, Daniele Eugenio; L., Criante; Simoni, Francesco
Editore: TAYLOR & FRANCIS LTD, 4 PARK SQUARE, MILTON PARK, ABINGDON, ENGLAND, OXON, OX14 4RN
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/36046

Characterization of polymeric materials for microholographic data storage
PROCEEDINGS OF SPIE, THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING
Autore/i: L., Criante; K., Beev; Lucchetta, Daniele Eugenio; Simoni, Francesco; S., Frohmann; S., Orlic
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51211

Visible and near-infrared characterization and modeling of nanosized holographic-polymer dispersed liquid crystals gratings
PHYSICAL REVIEW E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS
Autore/i: Vita, Francesco; A., Marino; V., Tkachenko; G., Abbate; Lucchetta, Daniele Eugenio; L., Criante; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: We have studied the electro-optical and angular behavior of holographic-polymer-dispersed liquid crystal gratings at different wavelengths, in the visible and in the near-infrared range. As usual in these kinds of materials, a strong polarization dependent behavior was observed. Our samples showed very high diffraction efficiency for p-polarized radiation at 1.55 m, which is very interesting for many possible applications in the telecom field. However, we also observed a very unusual behavior for visible p-polarized light and we try to suggest some explanation for that. By analyzing the angular dependence of the diffraction efficiency, we could measure the components of the permittivity modulation tensor and infer important information about the main parameters involved in the grating structure: the degree of phase separation and the anisotropy in the liquid crystal droplet distribution. In our opinion, this simple and nondestructive methodology can be very useful for studying these kinds of materials and getting information on their morphology, in view of optimizing their properties. Finally, we discuss the role of the refractive index optical dispersion in order to describe the behavior of these materials at different wavelengths. These remarks are especially important when properties in the infrared range are extrapolated from measurements in the visible.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51144

Compact Lasers Based on HPDLC Gratings
MOLECULAR CRYSTALS AND LIQUID CRYSTALS
Autore/i: Lucchetta, Daniele Eugenio; L., Criante; Francescangeli, Oriano; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: We report the fabrication technique and the main emission properties of two novel all-organic laser devices based on high-resolution reflection gratings written on holographic polymer-dispersed liquid crystal materials by means of conventional holographic techniques. The first type of laser is based upon a distributed Bragg-reflector configuration whereas the second one makes use of a distributed-feedback configuration. Different monomer/liquid-crystal/ photoinitiator mixtures are analysed and the main parameters affecting the grating reflectivity and the overall performances of these plastic mirrorless laser device are discussed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51767

Plastic lasers based on high resolution reflection gratings
Technical Digest, art. no. 1568362
Autore/i: Lucchetta, Daniele Eugenio; L., Criante; Francescangeli, Oriano; Simoni, Francesco
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/43539

Light amplification by dye-doped holographic polymer dispersed liquid crystals
APPLIED PHYSICS LETTERS
Autore/i: Lucchetta, Daniele Eugenio; L., Criante; Francescangeli, Oriano; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: (selected for June 7, 2004 issue of Virtual Journal of Nanoscale Science & Technology) In this letter we report a “one-step” fabrication technique of an optical active organic photonic band gap (PBG) structure allowing the onset of the amplification spontaneous emission effect and narrowing of the corresponding band. This result has been achieved through the addition of the dye rhodamine 6G to a standard holographic polymer dispersed liquid crystal pre-polymer mixture. The effects of the dye addition on the optical properties of the polymerized PBG structure have been analyzed. The spectra emitted by this optically active periodic structure have been studied as a function of the excitation energy.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51359

Polarization Indipendent Phase Modulation by a Film with Nano-Sized Droplets of Liquid Crystals
MOLECULAR CRYSTALS AND LIQUID CRYSTALS
Autore/i: V. A., Loiko; A. V., Konkolovich; Lucchetta, Daniele Eugenio; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/52952

Wavelength flipping in laser emission driven by a switchable holographic grating
APPLIED PHYSICS LETTERS
Autore/i: Lucchetta, Daniele Eugenio; Criante, L.; Francescangeli, Oriano; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: We report lasing from a simple wafer structure made of a thin layer of rhodamine 6G as active material and of a switchable holographic mirror, based on a reflection grating made of polymer dispersed liquid crystals. It is shown that switching-off the mirror reflectivity by application of a suitable voltage allows wavelength flipping of the laser emission by 10 nm.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/50061

Determination of small anisotropy of holographic phase gratings
OPTICS LETTERS
Autore/i: Lucchetta, Daniele Eugenio; Criante, L.; Simoni, Francesco
Editore: Optical Society of America:2010 Massachusetts Avenue Northwest:Washington, DC 20036:(800)762-6960, (202)223-8130, EMAIL: custserv@osa.org, INTERNET: http://www.osa.org, Fax: (202)223-1096
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/27139

Determination of small anisotropy of holographic phase gratings”, Optics Letters
OPTICS LETTERS
Autore/i: Lucchetta, Daniele Eugenio; L. CRIANTE AND F., Simoni
Editore: Optical Society of America:2010 Massachusetts Avenue Northwest:Washington, DC 20036:(800)762-6960, (202)223-8130, EMAIL: custserv@osa.org, INTERNET: http://www.osa.org, Fax: (202)223-1096
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/36048

Optical characterization of polymer dispersed liquid crystals for holographic recording
JOURNAL OF APPLIED PHYSICS
Autore/i: Lucchetta, Daniele Eugenio; Criante, L.; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/51336

X-ray diffraction study of dioleoylphosphatidylcholine-DNA-Mn2+ complexes
MOLECULAR CRYSTALS AND LIQUID CRYSTALS
Autore/i: Francescangeli, Oriano; Stanic, V; Lucchetta, Daniele Eugenio; Bruni, Paolo; Iacussi, M; Cingolani, F.
Classificazione: 1 Contributo su Rivista
Abstract: We have studied the structural properties of the triple complex dioleoylphosphatidylcholine-DNA-Mn2+ by means of synchrotron x-ray diffraction. The data revel a novel multilamellar structure similar to that recently found in cationic liposomes-DNA complexes. ne study of the bilayer undulations suggests that condensation of the DNA within the lipid bilayers reduces the flexibility of the lamellae in the complex and suppresses almost completely the undulatory fluctuations. These complexes are of grate interest for potential applications as synthetically-based nonviral carriers of DNA vectors for gene therapy.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/50764

Liquid Crystal Ordering by Freezing of Thermal Convection Motion in Polymer Dispersed Liquid Crystals
MOLECULAR CRYSTALS AND LIQUID CRYSTALS
Autore/i: Lucchetta, Daniele Eugenio; Francescangeli, Oriano; Lucchetti, Liana; Simoni, Francesco
Editore: Gordon & Breach Science Publishers:PO Box 90, Reading RG1 8JL United Kingdom:011 44 118 9520303, 011 44 118 9560080, 011 44 181 9560080, EMAIL: philip.bott@gbmis.gbhap.com, INTERNET: http://www.gbhap.com/pubdate, Fax: 011 44 118 9568211
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/27413

Phase-only modulation by nanosized polymer dispersed liquid crystals
JOURNAL OF APPLIED PHYSICS
Autore/i: Lucchetta, Daniele Eugenio; Karapinar, R.; Manni, A.; Simoni, Francesco
Editore: American Institute of Physics:2 Huntington Quadrangle, Suite 1NO1:Melville, NY 11747:(800)344-6902, (631)576-2287, EMAIL: subs@aip.org, INTERNET: http://www.aip.org, Fax: (516)349-9704
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/27135

Liquid crystal ordering by freezing of thermal convective motion in Polymer Dispersed Liquid Crystals
MOLECULAR CRYSTALS AND LIQUID CRYSTALS SCIENCE AND TECHNOLOGY. SECTION A, MOLECULAR CRYSTALS AND LIQUID CRYSTALS
Autore/i: Lucchetta, Daniele Eugenio; Francescangeli, Oriano; Lucchetti, Liana; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: This paper reports on the first observation of thermal convective motion in high-intensity photocured PDLC mixtures and demonstrates the possibility of LC ordering through the freezing of this thermal convective motion. The dependence of laser-cured PDLC films morphology on curing parameters such as light intensity, curing time, and sample temperature have also been studied. It is shown that the transition between ordered columnar and disordered turbulent motion is possible by increasing the laser beam intensity and that the flow patterns associated with both these regimes can be frozen by the photopolymerization process.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/50761

Enhanced Nolinear Optical Response of Liquid Crystals
NONLINEAR OPTICS for the INFORMATION SOCIETY
Autore/i: Simoni, Francesco; Francescangeli, Oriano; Lucchetta, Daniele Eugenio; Lucchetti, Liana
Editore: Kluwer Academic Pub
Luogo di pubblicazione: Dordrecht
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/72427

Nano-size Polymer Dispersed Liquid Crystals for Phase-Only Optical Modulation
MOLECULAR CRYSTALS AND LIQUID CRYSTALS
Autore/i: Lucchetta, Daniele Eugenio; Manni, A; Karapinar, R; Gobbi, Luigi; Simoni, Francesco
Editore: Gordon & Breach Science Publishers:PO Box 90, Reading RG1 8JL United Kingdom:011 44 118 9520303, 011 44 118 9560080, 011 44 181 9560080, EMAIL: philip.bott@gbmis.gbhap.com, INTERNET: http://www.gbhap.com/pubdate, Fax: 011 44 118 9568211
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/27411

SINE: surface induced nonlinear effects
MOLECULAR CRYSTALS AND LIQUID CRYSTALS SCIENCE AND TECHNOLOGY. SECTION A, MOLECULAR CRYSTALS AND LIQUID CRYSTALS
Autore/i: Lucchetti, Liana; Lucchetta, Daniele Eugenio; Francescangeli, Oriano; Simoni, Francesco
Editore: Gordon & Breach Science Publishers:PO Box 90, Reading RG1 8JL United Kingdom:011 44 118 9520303, 011 44 118 9560080, 011 44 181 9560080, EMAIL: philip.bott@gbmis.gbhap.com, INTERNET: http://www.gbhap.com/pubdate, Fax: 011 44 118 9568211
Classificazione: 1 Contributo su Rivista
Abstract: Pump-probe and TIR experiments have been performed on the dye-doped nematic liquid crystal 5CB, in order to study the basic mechanisms of the extraordinarily large nonlinear response recently reported. Experimental data show that light-induced modifications of the anchoring conditions can be the origin of the observed effect. The bulk reorientation due to the collective elastic behaviour of the liquid crystal gives then rise to the nonlinearity, which occurs without a direct optical torque on the molecular director in the bulk. We have called this effect SINE (Surface Induced Nonlinear Effect).
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/50997

Phase only modulation by Polymer Dispersed Liquid Crystals
JOURNAL OF APPLIED PHYSICS
Autore/i: Lucchetta, Daniele Eugenio; R., Karapinar; A. MANNI AND F., Simoni
Editore: American Institute of Physics:2 Huntington Quadrangle, Suite 1NO1:Melville, NY 11747:(800)344-6902, (631)576-2287, EMAIL: subs@aip.org, INTERNET: http://www.aip.org, Fax: (516)349-9704
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/36047

High intensity UV laser curing of Polymer Dispersed Liquid Crystals
MOLECULAR CRYSTALS AND LIQUID CRYSTALS SCIENCE AND TECHNOLOGY. SECTION A, MOLECULAR CRYSTALS AND LIQUID CRYSTALS
Autore/i: Lucchetta, Daniele Eugenio; Lucchetti, Liana; L., Gobbi; Simoni, Francesco
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/72440