Light Wave Propagation and Bragg Diffraction in Thick Polarization Gratings

Ono, Hiroshi; Sekiguchi, Toyokazu; Emoto, Akira; Shioda, Tatsutoshi; Kawatsuki, Nobuhiro

doi:10.1143/jjap.47.7963

Cited by 12 publications

(3 citation statements)

References 33 publications

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“…Our results demonstrate that a strong linear dichroism at the actinic optical wavelength, which is characteristic for light-sensitive LCEs and also for many other kinds of light-sensitive liquid crystalline materials, can drastically influence the volume-type polarization holographic recording in photo-responsive media. However, up till now this effect was mostly neglected [46,52]. In combination with strongly nonlinear recording kinetics associated with photo-bleaching, dichroism can lead to diffractive structures exhibiting various unusual phenomena, such as a profound minimum of the diffraction efficiency at the Bragg angle, which was the subject of our present investigation.…”

Section: Discussionmentioning

confidence: 92%

Peculiar behaviour of optical polarization gratings in light-sensitive liquid crystalline elastomers

Prijatelj

Ellabban

Fally

et al. 2016

Opt. Mater. Express

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The angular dependence of the diffraction efficiency of volumetype\ud holographic gratings recorded in a single-domain light-sensitive liquid\ud crystalline elastomer was investigated. Usually this dependence is expected\ud to be very similar for intensity gratings and for polarization gratings.\ud However, our measurements resolved a profound difference between the\ud two types of the gratings: a typical Bragg peak of the diffraction efficiency\ud is observed only for intensity gratings, while polarization gratings exhibit a\ud profound dip at the Bragg angle. The appearance of this dip is explained by\ud strongly anisotropic optical absorption of the actinic light during the\ud recording process

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Section: Discussionmentioning

confidence: 92%

Peculiar behaviour of optical polarization gratings in light-sensitive liquid crystalline elastomers

Prijatelj

Ellabban

Fally

et al. 2016

Opt. Mater. Express

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“…14,15,74,76 If two laser beams interfere, various interference patterns are observed depending on the polarization state. For example, parallel linearly polarized beams, such as a combination of s,s-polarization, give intensity gratings.…”

Section: Nmmentioning

confidence: 99%

Rewritable holograms based on azobenzene-containing liquid-crystalline polymers

Shishido

2010

Polym J

163

108

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The design and preparation of azobenzene-containing polymers showing a large photoinduced change in refractive index, and their applications to rewritable Raman-Nath and Bragg holograms are reviewed. Optically transparent films with a thickness of 4200 lm have been prepared with random copolymers, which contain photoresponsive and amplifying components in the side chain. Various azobenzene chromophores are used as the photoresponsive component. Cyanobiphenyl and tolane moieties are incorporated as the amplifying component, which enhances the change in refractive index triggered by the azobenzene. When two writing beams are made to overlap in the film, a periodic change in refractive index is induced, and an incident probe beam is diffracted at B100% diffraction efficiency. The recorded holograms can be erased by thermal treatment or by photoirradiation with a single writing beam. Angular multiplicity is discussed from the viewpoint of high-density information storage. Keywords: azobenzene; grating; hologram; liquid crystal; refractive index INTRODUCTION Holograms, in which we can observe natural three-dimensional (3D) images without eyeglasses, have been of great interest from the viewpoint of 3D television. [1][2][3] In addition, other photonic applications such as holographic memory, optical switch and waveguide have been proposed. [3][4][5][6][7][8][9] The holograms can be categorized into two types: (1) Raman-Nath type and (2) Bragg type. The Raman-Nath hologram recorded in a thin film causes multiple diffraction of an incident beam, leading to low diffraction efficiency (o34%). On the other hand, the Bragg hologram shows a single diffraction, which enables 100% diffraction efficiency. Furthermore, angular multiplicity can be used in the Bragg hologram. Therefore, thick films are suitable for holograms with high diffraction efficiency. The diffraction efficiency also depends on a photoinduced change in refractive index of the film. If materials in which a large change in refractive index can be induced by light can be prepared, the performances parameters such as diffraction efficiency, response and multiplicity of the holograms can be enhanced. How can we induce the change in refractive index efficiently? In an isotropic material, the change in refractive index by photoirradiation is rather small and the efficiency is not high. In addition, the material is theoretically polarization inactive. On the other hand, an anisotropic material could show birefringence. By controlling their molecular alignment by photoirradiation, a large change in refractive index and high diffraction efficiency can be obtained. Furthermore, an anisotropic material shows polarization activity. Therefore, we can expect the fabrication of high-performance holograms by photoinduced alignment of anisotropic molecules.

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“…Basically, these schemes are based on the Bragg condition in volume hologram provided by a thick medium. In addition to these conventional schemes, polarization multiplexing is another possibility, which makes use of the polarization state of light waves in a polarization-sensitive recording medium [2][3][4][5][6][7]. By combining the conventional holographic multiplexing and the polarization multiplexing in a polarization-sensitive medium the storage capacity can be potentially increased.…”

Section: Introductionmentioning

confidence: 99%

Volume polarization holographic recording in thick photopolymer for optical memory

Lin¹,

Cho²,

Chou³

et al. 2014

Opt. Express

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Based on a vector wave theory of volume holograms, dependence of holographic reconstruction on the polarization states of the writing and reading beams is discussed. It is found that under paraxial approximation the circular polarization holograms provide a better distinction of the reading beams. Characteristics of recording polarization holograms in thick phenanthrenequinone-doped poly(methyl methacrylate) (PQ/PMMA) photopolymer are experimentally investigated. It is found that the circular polarization holographic recording possesses better dynamic range and material sensitivity, and a uniform spatial frequency response over a wide range. The performance is comparable to that of the intensity holographic recording in PQ/PMMA. Based on theoretical analyses and the material properties, a polarization multiplexing holographic memory using circularly polarization recording configuration for increasing storage capacity has been designed and experimentally demonstrated.

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Light Wave Propagation and Bragg Diffraction in Thick Polarization Gratings

Cited by 12 publications

References 33 publications

Peculiar behaviour of optical polarization gratings in light-sensitive liquid crystalline elastomers

Peculiar behaviour of optical polarization gratings in light-sensitive liquid crystalline elastomers

Rewritable holograms based on azobenzene-containing liquid-crystalline polymers

Volume polarization holographic recording in thick photopolymer for optical memory

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