川月 喜弘

Benzylideneaniline (BA) derivatives are transparent in the visible region and exhibit a photoreactivity toward trans-cis photoisomerization. We evaluated polarized photoreaction and properties of the polymer complex composed derivative of BA with 4-4' substituent. Polarized photoreaction proceeded composite films of all. For example, p-[p-(methoxy benzylidene)amino]phenol (BA2)/poly-4(vinylprridine) (P4VP) composite films showed the photoreaction using linearly polarized (LP)-UV light and minus photoinduced optical dichroism (ΔA=A_||-A_⊥).

A photo-cross-linkable liquid crystalline polymer (PMCB6M) film is applicable to LC alignment layer and it is important to investigate reorientation behavior at the near surface of reoriented PMCB6M film. In this study, reorientation behavior of PMCB6M film in bulk and at near surface was performed by UV-vis spectroscopy and NEXAFS.

Holographic diffraction gratings were recorded in a low-molecular-weight nematic liquid crystal (LC) doped with trace amounts of photocrosslinkable polymer LC (PPLC) by using a UV laser. We measured diffraction properties of the recorded gratings, and confirmed that polarization gratings consist of spatial distribution of optical anisotropy were induced in the LC cell due to the axis-selective photocrosslinking of the PPLC. In addition, it was demonstrated that the diffraction properties of the gratings can be controlled by applying an external voltage to the LC cell.

We prepared novel polymethacrylates containing phenyl cyano vinyl terthiohene side chain and evaluated their mesomorphic propeties. Additionally, we synthesized oligothiophene with the same structure and explored their alignment behavior on photoaligned polymer films.

Schiff base compound is well known as liquid crystalline material, and photoisomerization can occur. However, photoreaction of liquid crystalline polymers (LCPs) with schiff base side group have not been investigated. In this presentation, we synthesized LCPs with schiff base side group and investigated the axis-selective photo reaction.

In this study, we synthesized new hydrogen-bonding asymmetric luminophores with different site of substitution, and evaluated their optical properties, orientation properties on hydrogen-bonding photo-alignment polymer film by UV-vis absorption spectra, fluorescent spectra, and fluorescence lifetime measurements.

We prepared various chromophores containing hydrogen bonding unit and investigated their change in photoluminescent properties induced by mechanical stimuli. We reported photoluminescent color and lifetime tuning of complex compound of dyes and acids.

This letter describes photoalignment layers showing high photosensitivity at linearly polarized (LP) 313 nm light. Irradiation of LP 313 nm light followed by annealing induced a molecularly oriented structure of the photoalignment layers, which showed excellent image sticking property due to azimuthal anchoring energy of the IPS LC cell using them. © 2013 Society for Information Display.

Four kinds of liquid crystalline polymers (LCPs) with phenyl benzoate side groups were synthesized and their photoinduced reorientation behavior was investigated using linearly polarized (LP) UV light based on the axis-selective photo-Fries rearrangement and thermally induced self-organization of the mesogenic side groups of the materials. Due to different effect of the axis-selectively photoreacted side groups, reorientation direction and its performance depended on the chemical structure of the side groups. Both alignment ability and the molecular rotation of the photoreacted side groups played an important role in the reorientation behavior. Copyright © Taylor and Francis Group, LLC.

We have carried out experimental and theoretical characterization of the dynamics of the vector holographic recording in azobenzene-containing polymeric films by observation of the temporal polarization states of the diffraction beams. Two types of mechanisms, i.e., linear polarization induced birefringence and migration induced rotation birefringence, are introduced in the present paper, and transitional reorientation and rotation of molecules during vector holographic recording in azobenzene-containing polymeric films are successfully determined. © 2013 The Japan Society of Applied Physics.

We investigated the photorefractive performance of the polymer dissolved liquid crystalline composite (PDLCC), in which liquid crystalline polymer and low-molar-mass liquid crystal are miscible without phase separation, doped with three kinds of fullerene derivatives with different length of alkyl groups. The photorefractive performance was improved for the photorefractive PDLCC doped with fullerene derivatives with long length of alkyl groups. The photorefractive grating formation originates in the cooperative reorientation of the liquid crystalline director and the space charge field was estimated using the elastic continuum theory and the field for the PDLCC doped with the functionalized fullerene with longer alkyl side groups was larger than that for the PDLCC doped with conventional fullerene C60. © 2013 Elsevier B.V.

The photoinduced reorientation and surface relief (SR) formation behaviors of a novel photosensitive polymer, which was transparent in visible region, were investigated using linearly polarized-313-nm light and holographic exposure with a 325-nm He-Cd laser. The polymer was comprised of photosensitive 4-methoxy-N-benzylideneaniline side groups, and exhibited a sufficient photoinduced molecular reorientation with a birefringence of 0.11. Holographic exposure generated a SR structure, which had a periodical molecular reorientation that depended on the polarization of the interference beams. The generated SR height was ∼212 nm, and the inscription of a double holographic exposure yielded a two-dimensional SR structure. © 2013 Author(s).

Many types of photoreactive polymers have been investigated to regulate their molecularly orientated structures for polarization-controlled optical and display applications. Herein, we demonstrate the axis-selective photoreaction of thin films and their molecular reorientation behaviors using four types liquid crystalline poly(meth)acrylates with phenyl benzoate side groups and linearly polarized (LP) 248 nm light. These simple liquid crystalline polymers (LCPs) exhibit sufficient photoinduced molecular reorientations. Photoinduced molecular reorientation based on an axis-selective photo-Fries rearrangement is simultaneously generated with an in-plane order parameter (S) up to 0.33 when the irradiation temperature is in the lower part of the LC temperature range of the material, but multidomain formation of the mesogenic groups inhibits reorientation. To prevent thermally generated multidomain formation, an axis selective photoreaction of an amorphous film followed by thermally generated self-organization processes effectively induce molecular reorientation with S up to 0.71 and birefringence (Delta n) similar to 0.16

A subwavelength-period grating made in an intrinsic anisotropic medium was experimentally fabricated by means of imprinting and subsequent photoinduced molecular alignment of photocrosslinkable polymer liquid crystals (PCLC). Optical properties including the total birefringence and optic axis were theoretically and experimentally investigated by varying the crossing angle between the grating vector and the polarization azimuth of linearly polarized ultraviolet light for the photoalignment of PCLC. The total birefringence and optic axis were wellcontrolled by both form birefringence due to the subwavelength-period grating structure and intrinsic birefringence induced by photoalignment of PCLC. The finite-difference time-domain (FDTD) method was an effective tool for characterizing the optical properties of a subwavelength-period grating made in an intrinsic anisotropic medium. © 2012 Optical Society of America.

For realizing polarization-multiplex holographic recordings we have proposed theory and performed experiments on characterizing optical properties of vector holograms, which are recorded using both intensity- and polarization-modulated interference light, by introducing two susceptibilities of isotropic (α) and anisotropic (β) phase changes due to irradiation of polarized light on azobenzene-containing polymers as polarization-sensitive medium. The vector holograms were experimentally recorded using two radially polarized beams as inhomogeneous polarized light and polarized diffraction patterns from the resultant vector holograms were well-explained by our proposed theory. © 2012 The Japan Society of Applied Physics.

It is very important for realizing the polarization-multiplex holographic memory to clarify the optical properties of vector holograms recorded using the inhomogeneous polarized beams. In the present paper we present a simple yet useful method using the radially polarized writing beams to systematically investigate the optical properties of complicated vector holograms and preliminary data about effects of polarization azimuth of writing beams on diffraction properties. The diffraction properties of the vector holograms written in the azobenzene-containing polymers were strongly dependent on the angle between the grating vector and polarization azimuth of the writing beam. Considering the above-mentioned dependence, the theoretical calculation on the basis of Jones calculus revealed optical properties of the vector holograms written by various types of radially polarized beams. © 2012 The Japan Society of Applied Physics.

Anisotropic diffractive gratings formed by birefringent molecular alignment are fabricated by a holographic technique using a photo-cross-linkable liquid crystalline copolymer (PLCCP). Depending on the exposure energy used for holographic recording, bright or dark regions of the interference fringe can be chosen for the molecular-aligned region, analogous to positive- and negative-type photoresist processing in photolithography. In conjunction with simultaneously generated surface relief gratings, the anisotropic refractive index modulation inherent in the PLCCP film exhibits different diffraction properties depending on the incident beam polarization. The anisotropic refractive index grating profiles are quantitatively presented for two cases determined by the exposure energy, based on the Fourier analysis of diffractive optics. The selection of different grating formations selected by varying only the exposure energy could provide a strategy for the fabrication of functionalized diffractive optical elements. © 2012 Springer-Verlag.

A photomobile polymer fiber containing anthracene carboxylic acid was prepared from a mixture of commercially available compounds and the photomechanical effects of the fiber were investigated. Upon exposure to UV light, the fiber bent toward the actinic light source owing to [4+4] photodimerization of the anthracene unit, which is similar to that for anthracene side-chain polymers. In addition, the photomechanical properties of the fiber were significantly enhanced by the introduction of liquid-crystalline (LC) properties through the addition of low molecular weight LC acids. © 2012 The Society of Polymer Science, Japan (SPSJ) All rights reserved.

A new asymmetric polarization holography was conducted to form a blazed surface relief (SR) structure in a polymethacrylate film comprised of 4-methoxyazobenzene side groups using asymmetrically controlled polarized 325nm He-Cd laser beams. Asymmetrical molecular migration, which generated the blazed SR structure, was achieved by adjusting the influence of both the intensity and polarization distributions of the two beams on molecular migration. © 2012 The Japan Society of Applied Physics.

We present a simple yet efficient method to automatically fabricate the twisted nematic structure by one-step exposure on an empty glass cell coated with photocrosslinkable polymer liquid crystal (PCLC) films. The resultant photoalignment directions of two substrates can be orthogonal to each other by controlling the difference between the exposure energy for upper and lower PCLC films and the twisted nematic (TN) structure can be automatically fabricated. The vector grating liquid crystalline cell with TN structure was also fabricated by means of a developed method, and the diffraction properties were well explained by the theoretical calculation on the basis of Jones calculus. © 2012 Optical Society of America.

Reversible addition-fragmentation chain transfer (RAFT) polymerization is used to synthesize diblock and random copolymers of poly[(2-trifluoroethyl methacrylate)-co-(methacrylic acid)]. Copolymer films doped with fluorene derivatives comprised of pyridine groups exhibit reversible photoluminescent (PL) color tuning by adjusting the location of fluorene derivatives in H-bonds or non-H-bonds environments. The composite films exhibit green and blue photoluminescence with and without effective H-bonding between the pyridine ring in the fluorene derivative and the carboxylic acid side group, respectively. At elevated temperatures, the H-bonded structure dissociates and the fluorene derivative migrates to the hydrophobic block in the diblock polymer, and they do not form H-bonds upon cooling. However, re-formation of H-bonds also occurs upon cooling random copolymers. Moreover, adjusting the annealing temperature and the solvent annealing reversibly tunes the PL color in the diblock copolymer composite films.

We demonstrate a polarization imaging screen using vector gratings by ultraviolet laser direct writing of polarized-light-induced optical anisotropy in photocrosslinkable polymer liquid crystals. For realizing a polarization-sensitive diffraction in the image screen, spatial distribution of the optical anisotropy has been designed, and the right- and left-hand side circularly polarized optical image are clearly reconstructed as the +1st- and -1stordered diffraction according to the theoretical expectation. © 2012 The Japan Society of Applied Physics.

Surface relief (SR) formation in polymethacrylate films with azobenzene side groups was investigated via a holographic method using 325nm He-Cd laser, which generated stable cis isomers. Because the azobenzene molecules underwent both photoinduced reorientation and photoisomerization according to the polarization and intensity distribution of the interference beams, formation of the SR structure depended on both the exposure energy and polarization distribution. For intensity holography, both the photogenerated cis isomer distribution and polarization direction of the exposed beams played important roles in SR formation, which accompanied the molecularly reoriented SR structure. For polarization holography, a small SR structure accompanied the periodical molecular orientation in the initial stage of polarization holography due to uniform distribution of cis isomer. However, a SR structure larger than that generated by intensity holography was produced in the photostationary state. © 2012 The Japan Society of Applied Physics.

Nonlinear light propagation in a dye-doped nematic liquid crystal (LC) was investigated experimentally. A laser beam with wavelength far from the absorption peak of the material was coupled into an LC cell with homogeneous alignment, and the propagation in the cell was observed. When the polarization azimuth of the incident light was orthogonal to the orientation direction of the LC, soliton-like propagation was obtained for milliwatts of light power in spite of the low absorption. We clarified that the observed nonlinearity is due principally to the photothermal effect enhanced by the dye.

It's well known that surface relief (SR) structures in azobenzene polymer films are fabricated due to molecular migration by holography with intensity and polarization patterns of two beams interference. Blazed SR gratings, which exhibit asymmetric SR structures, exhibit asymmetrical diffraction properties, so those are useful as diffraction optical devices. Because molecular migration occurs symmetrically according to the symmetrical interference pattern, the blazed SR formation using conventional holographic techniques have not been reported. In this work, we demonstrated control of SR structure in azobenzene polymer films using controlled polarized two-beam interference.

The cooperative molecular reorientation in methacrylate copolymer films comprised of hexamethylene spacer groups terminated with photoreactive hydrogen (H) bonded 4-oxycinnamic acid (CA) and 4-oxy-4'-methoxyphenylbenzoate (MBe) in their side chains was investigated by irradiating with linearly polarized ultraviolet light (LPUV) and subsequent annealing. Both CA and MBe side groups were miscible in all the copolymer composition, and axis-selective photoreaction of both side groups was observed. A thermally enhanced cooperative in-plane orientation of both side groups perpendicular to the polarization (E) of LPUV light was obtained when the exposed films were annealed in the liquid crystalline temperature range of the copolymers. The generated birefringence of the reoriented film was 0.12 - 0.16 and the processing temperature was controlled between 85 and 165 degrees C by adjusting the copolymer composition.

We prepared novel photoreactive liquid crystalline (LC) polymer via polymer reaction. The cinnamic acid activated ester easily converted to amide by mixing with amine derivative and solubility of the polymer reduced due to hydrogen bonding. Upon exposure to linearly polarized ultraviolet light and subsequent annealing, the LC cinnamide exhibited axis selective photoreaction and following thermally amplification of molecular alignment. However, photoreactivity, LC stability and thermal amplification behavior of the cinnamide group were lower than that of original cinnamic acid group, suggesting that the lateral hydrogen bonding disturbs molecular reorientation behavior.

Photoinduced cooperative molecular reorientation in liquid crystalline (LC) methacrylate copolymers with hexamethylene spacer groups terminated with 4-methoxyazobenzene and benzoic acid in the side chain, and the influence of the copolymerization ratio on the thermally enhanced photoinduced molecular reorientation behavior were investigated. All copolymers exhibited a LC phase, and sufficient thermally enhanced photoinduced in-plane molecular reorientation was achieved by irradiating with linearly polarized (LP) UV light and subsequent annealing when the azobenzene composition was greater than 5 mol%. Adjusting the exposure energy and the polarization of the LPUV light attained a patterned oriented structure, which can be useful as alignment layer for functional materials. Finally, a patterned birefringent film was fabricated using photocurable liquid crystals on the patterned copolymer film.

This paper describes the photoalignment behavior of liquid crystals (LCs) on a photoalignment layer containing a new photosensitive polyamic-ester derivative (PAE) under several fabricating conditions. Irradiating PAE films with a linearly polarized (LP) UV light at temperatures over 160 degrees C dramatically accelerated the photoreaction and photoinduced optical anisotropy. Furthermore, an improvement of the LC alignment quality was observed on PAE films when films were irradiated over 160 degrees C.

Symmetric and asymmetric holographies with various polarization conditions were conducted to investigate a formation of blazed surface relief (SR) structures in a polymethacrylate film comprised of 4-methoxyazobenzene side groups using polarized 325 nm He-Cd laser beams with controlled polarizations. Because molecular migration to form the SR structures in the film was caused by both intensity and polarization distributions of the holographic beams, asymmetric molecular migration occurred when the difference in the phase modulation of the intensity and polarization distributions existed. Adjusting the polarization conditions, and the crossing angle and azimuths of the polarization direction of the main axis of the two beams controlled the blazed structure and the SR height. © 2012CPST.

Polymethacrylate copolymers, which have hexamethylene spacer groups terminated with 4-methoxyphenyl-4'-oxycinnamate (MPC) and 4-oxybenzoic acid (BA) in the side chain, were synthesized. Thin films underwent thermally enhanced photoinduced cooperative molecular reorientation using linearly polarized ultraviolet (LPUV) light and subsequent annealing. Moreover, low exposure energy (4-80 mj cm(-2)) and annealing temperature (<140 degrees C) provided sufficient cooperative molecular reorientation of both side groups with a large reorientational order (S > 0.5). Tuning the copolymer composition adjusted the birefringence (An) of homogeneously reoriented films between 0.10 and 0.22 at 517 nm. Finally, a phase retarder (Delta nd = 130 nm) using an oriented copolymer on a triacetylcellulose (TAC) film substrate, which exhibited a thermal stability up to 140 C, was fabricated. (C) 2011 Elsevier Ltd. All rights reserved.

The orientation of molecules in photoinduced liquid crystalline polymer film was studied by means of a thermal nanoimprinting technique using a SiO2/Si mold with a line-and-space (L&S) pattern. If nanoimprinting reorients molecules in photoinduced liquid crystalline polymer, unique characteristics may result from carrying out nanoimprinting and linearly polarized UV (LPUV) irradiation at the same time. We found that the imprinted photoinduced polymer was oriented parallel to the line pattern on the mold. Furthermore, we found that photoinduced liquid crystalline polymer films that were pre-aligned by LPUV irradiation and a heat treatment could be reoriented by thermal nanoimprinting. (C) 2011 Elsevier B.V. All rights reserved.

Molecularly oriented surface relief (SR) structures in photo-crosslinkable liquid crystalline copolymer films were fabricated using a 325 nm He-Cd laser with p-p and s-s polarized intensity holographic beams. The SR height increased as the exposure energy increased. In contrast, the molecular orientation structure depended on the exposure dose. For all doses, molecular migration from the lower exposure region to the higher one was due to the difference in the crosslinking density. The SR height reached up to 280 nm for a film that was initially 1.0 urn thick. The diffraction efficiency depended on the fabricated SR grating, while the difference in the molecular reorientation area and the direction of the SR gratings explained the diffraction properties. © 2011 The Japan Society of Applied Physics.

The thermally enhanced photoinduced molecular reorientaiion based on an axis-selective photo-Fries rearrangement was explored for the first time using three liquid crystalline polymethacrylates with 4-(2'-(4 ''-methoxyphenyl)ethynyl)phenyl benzoate side groups (la), 4-methoxybiphenyl benzoate side groups (1b), and 4-methoxyphenyl benzoate side groups (1c). All the polymeric films exhibited an axis-selective formation of the photo-Fries products at the phenyl benzoate derivatives side groups by irradiating with linearly polarized (LP) UV light. Annealing the films in the liquid crystalline temperature range of the material greatly amplified the photoinduced small optical anisotropy of the irradiated films. For la and 1b, the photoinduced small anisotropy was amplified in a direction parallel to the polarization (E) of LPUV light and the reorientational order (S) was greater than 0.7. In contrast, the orientation direction was perpendicular to E for 1c (S similar to 0.57). Finally, a simple double-exposure method using one photomask without alignment was performed to fabricate a patterned quarter-wave plate.

We synthesized a new oligothiophene derivative with pyridine end groups and investigated their optical properties. Upon adding an aqueous polystyrene sulfonic acid solution, it forms homogeneous polymer complex films with protonated structure. Furthermore, reversible color change in photoluminescence in response to a base due to reversible protonation of pyridyl end groups in oligothiophene was demonstrated, which can be applied to acid sensors.

We present a simple yet efficient, competitive, and practical fabrication method, called "polarizer rotation exposure", for preparing vector gratings with a large area and a high diffraction efficiency. The polarization states of ultraviolet light were modulated by rotating the polarizer, and the resultant ultraviolet light was line-focused onto hydrogen-bonded liquid crystalline polymer films set on a linear stage. Mesogenic molecules in the polymer films were reoriented according to the light electric vectors, and vector gratings in which the optical anisotropy is periodically modulated were fabricated by the polarizer rotation exposure method. © 2011 The Japan Society of Applied Physics.

This paper demonstrates formation of surface relief (SR) gratings and crossed SR gratings with molecularly oriented structure using photo-cross-linkable liquid crystalline copolymer films by means of holographic exposure of 325 nm He-Cd laser beams combined with linearly polarized (LP) UV light. For the intensity holography using He-Cd laser, SR gratings were formed after annealing the exposed films, where the molecular migration from the lower to the higher-exposed region occurred. The reorientational part and SR height were dependent on degree of the photoreaction. When the exposure doses were low, molecular reorientation at the convex region was generated. In contrast, higher exposing doses resulted in the molecular reorientation at the concave area. The resulting gratings showed polarization sensitivity for diffraction efficiencies of the probe light beam according to the molecularly reorientation direction. Furthermore, multi-holographic exposure yielded crossed SR gratings with reoriented structure according the polarization direction of He-Cd laser beams, which exhibited multi-functional diffractions. Furthermore, when combining the multi-holographic exposure and the unidirectional LPUV light exposure, crossed SR grating with multi-directionally oriented film structure was generated., where the whole area was reoriented.

Anthraccene liquid-crystalline (LC) polymer fibers were synthesized and their photomechanical properties were explored. The polymer fiber bent toward a light source upon exposure to UV light due to photodimerization of anthracene moieties. They contracted with decrease in optical anisotropy along their fiber axis when they were heated above their LC-isotropic phase transition temperature.

Surface relief (SR) gratings with a molecularly oriented structure and pure polarization hologram were fabricated on a photo-cross-linkable liquid crystalline copolymer using a 325-nm laser with various two-beam polarization modes. For intensity holography, the polarization information from the two beams simultaneously provided the molecular motion and molecular reorientation the SR height reached up to 186 nm and the concave area revealed a molecular reorientation when the exposing beams were linearly polarized. In contrast, SR formation was negligible for polarization holography when molecular reorientation due to the polarization modulation was observed. The resulting polarization gratings changed the polarization properties of the diffraction beams, and their diffraction efficiency was reached 24%, which agreed with theoretical expectations. © 2010 Elsevier Ltd. All rights reserved.

Molecular orientation in a photo-crosslinkable liquid crystalline polymer (PLCP) film was explored by a thermal nanoinprinting technique using a SiO 2/Si mold with a line-and-space (L&amp S) pattern. A molecular oriented structure was confirmed by polarization optical microscopy and diffraction efficiency measurements, at which the reoriented direction was parallel to the mold lines. We demonstrated thermal nanoimprinting on prealigned PLCP films by linearly polarized UV (LPUV) and evaluated the optical characteristics of imprinted PLCP films. As a result, the prealigned PLCP films were reoriented by thermal nanoimprinting. © 2010 The Japan Society of Applied Physics.

Anthracene polymers containing flexible side chains were prepared and their photomechanical properties were investigated. The glass transition temperature of the polymers decreased and the photoreactivity at room temperature was enhanced with an increase of the flexible side chain content. When the polymer was formed into a fiber shape and illuminated with UV light, it bent toward the actinic light source. The deformation was investigated using a thermomechanical analyzer, which revealed that the polymers undergo fast expansion and slow contraction in response to UV light, due to the thermal expansion and photodimerization of the anthracene moiety, respectively.

We theoretically investigate optical birefringence originating from subwavelength structures in intrinsic birefringent media. Assuming alternating layers of isotropic and anisotropic materials, the propagation of optical waves is simulated on the basis of the finite difference time domain method. Optical polarization changes throughout the structure reveal the birefringence of the layered structure as a whole. In addition, the birefringence is also analyzed on the basis of effective medium theory. The results indicate that the optical birefringence of the structure as a whole can be modified by the magnitude and direction of the intrinsic birefringence of the anisotropic layers. This theoretical prediction will be useful for microand nanofabrication in optical devices. © 2010 Optical Society of America.

Three fluorene (FL) derivatives with pyridine end groups were synthesized to control the photoluminescence (PL) wavelength and polarized light emission using a photoreactive H-bonded polymer containing cinnamic acid side groups (P6CAM). The FL derivatives, which possessed pyridine end groups, formed H-bonds with cinnamic acid, and changed the PL behavior of the derivatives. The controllability lambda(max) of the PL depended on the position of the N-atom at the pyridine end group and the degree of the photoreaction of the P6CAM. For F1, lambda(max) of the PL was tuned from 470 to 518 nm. Employing P6CAM as the photoalignment layer to reorient the cinnamic acid side groups realized polarized PL up to PL(parallel to)/PL(perpendicular to) = 3.9. Furthermore, photopatterning of the PL color and the direction of the polarized light emission using patterned P6CAM films were demonstrated.

We achieved facile surface relief (SR) formation with symmetrical and asymmetrical structure in photoreactive polymer/benzophenone (BP) monomer composite films by holographic exposure to 325-nm He-Cd laser beams. Under holographic exposure, photo-excited BP molecules induced photo-crosslinking of the composite film, incorporating BP molecules into the polymer and generating molecular motion, resulting in SR formation. The height of the SR depended on the polymer/BP ratio, and reached 550 nm. Furthermore, slantwise exposure resulted in asymmetrical SR formation. The resultant SR gratings were transparent to visible light and thermally stable up to 95 °C. © 2010 The Japan Society of Applied Physics.

We present a highly functionalized photorefractive device consisting of fullerene (C60) -doped nematic liquid crystals (NLCs) on silver sulfide thin films. Either stable holograms or real-time holography is possible depending on the polarity of an external electric field. When certain direction of external field is applied to the device under irradiation by interference field, photoexcited charges are recombined with silver ions at the boundary between the silver sulfide and NLCs. The resulting interface structures reorient the NLC molecules and holographic gratings are stably memorized. When the polarity of the external field is reversed, normal photorefractive holographic gratings are formed. © 2010 American Institute of Physics.

A new photo-cross-linkable liquid crystalline polymer (PLCP) comprised 4-methoxycinnamoyloxy groups connected with a bistolane side group was synthesized to investigate thermally enhanced photoinduced molecular reorientation of a thin film with linearly polarized (LP) 365. nm light exposure. Due to the axis-selective photoreaction of the cinnamate groups followed by the thermally induced self-organization, large molecular reorientation parallel to the polarization of LPUV light (S&gt 0.6) and large birefringence at the non-resonance region (Δ n=0.34 at 632.8. nm) were obtained. The obtained Δ n value is the largest among transparent PLCPs in the visible region. The influence of the degree of photoreaction and the annealing temperature on the thermally enhanced molecular reorientation behavior was explored in detail. Finally, for an application of thin optical devices using the PLCP films, pure polarization holographic gratings with large birefringence, which showed periodic molecularly oriented structure, were fabricated using a 325. nm He-Cd laser in various polarization modes and characterized their optical properties. © 2010 Elsevier Ltd.

We prepared photomobile polymer fibers with anthracene side groups and explored their photomechanical properties. Upon irradiation with UV light, the fiber bent toward an actinic light source. The degree of bending and photoreaction were strongly affected by temperature. The fiber can dose the deformation without macroscopic change at room temperature and release them on heating.

Effects of recording wavelength on the recently proposed (Sasaki, 2008) three-dimensional vector holograms, in which the optical anisotropy is three-dimensionally modulated, are presented experimentally and theoretically. The polarization states of the interference light are three-dimensionally modulated due to both the polarization interference and optical anisotropy in the recording medium. These spatial distributions of the polarization states and the resulting diffraction properties in the three-dimensional vector holograms are strongly dependent on the recording wavelength. Theoretical consideration based on the finite-difference time-domain (FDTD) method reveals the mechanism of the optical characteristics of the three-dimensional vector holograms recorded by various kinds of light sources with different wavelengths. © 2009 Elsevier B.V. All rights reserved.