A polysiloxane‐based photorefractive polymer with high optical gain and diffraction efficiency*

Zobel, O.; Strohriegl, Peter; Eckl, M.; Haarer, D.

doi:10.1002/adma.19950071108

Cited by 70 publications

(37 citation statements)

References 18 publications

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“…[5,6] Boron nitride is a chemically inert and thermally resistant material, and BN nanotubes have been widely researched. [7] If aluminum borate whiskers are coated with BN coating forming nanocables, the interfacial reaction between the aluminum borate whisker and the matrix may be prevented. This assumption prompted us to synthesize boron nitride coated aluminum borate nanocables.…”

Section: Methodsmentioning

confidence: 99%

Undoped Photorefractive Ferroelectric Liquid Crystal

et al. 2003

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Light-sensitive media constitute a class of materials that are extensively studied because of their technological relevance for a variety of applications. In particular, the non-local reversible refractive index control by light, which is possible in substances exhibiting photorefractive properties, is of wide interest for real-time holography.[1] Photorefractivity is observed in photoconductors when a spacially non-uniform light exposure generates charge carriers which redistribute over macroscopic distances. This causes an electric field, which affects the refractive index of the material. Driven by the aim of obtaining low-cost and easily processable media, many efforts have been devoted to the understanding of the photorefractive properties of organic amorphous glasses [2±4] and polymers, [5±9] followed more recently by the interest in photorefractive liquid crystals. [10] Mesophases are attractive for photorefractivity because of their high spontaneous birefringence and the wide variety of field-induced refractive index control mechanisms.[11] The first liquid crystals studied for their photorefractive properties were bulk [12±14] and dispersed [15,16] nematic materials, but in the last years a number of investigations have showed that smectic phases can be photorefractive as well. [17±19] In particular, studies were carried out on chiral smectic A and C phases, where the mechanisms of field-induced fast molecular reorientation are connected with an induced or permanent polarization, respectively. [20] In all the reported investigations, the liquid-crystalline phase is not intrinsically photoconducting, so that the space±charge field set up is achieved either by dissolving a light sensitizer (and often a charge-transport agent as well) within its bulk, or by placing the mesophase within (like in dispersed systems), or between layers of, a photoconducting material. In this work the first example of a smectic mesophase that exhibits photorefractive behavior without any doping will be presented. It will also be shown that the observed photorefractive performance is larger than that previously reported for doped systems. Our approach is based on two recent results: the observation of photorefractivity in amorphous glasses formed by cyclopalladated complexes [21] and the synthesis of a new complex, with a closely related molecular structure, which exhibits a chiral smectic C phase. [22] The mesomorphic behavior of this complex, with a structure shown in Figure 1a and called for simplicity AzPdL, was investigated by optical microscopy, differential scanning calorimetry (DSC) and low-angle X-ray diffraction measurements. The observed transition temperatures between the isotropic (I), cholesteric (N*), chiral smectic C (SmC*) and crystalline (Cr) phases are included in Figure 1a.

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Section: Methodsmentioning

confidence: 99%

Undoped Photorefractive Ferroelectric Liquid Crystal

et al. 2003

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“…A remarkable result based on polysiloxanes (PSX) with pendant carbazole groups was obtained by Zobel et al 50) The glass transition temperature of this system could be controlled in a wide range of -45 to 51 8C by varying the length of the alkyl spacer linking the carbazole to the polymer backbone. Doped with DMNPAA (43 wt.-%) and TNF (1 wt.-%), this composite exhibited a net optical gain of 220 cm -1 and a diffraction efficient of 60%.…”

Section: Polymeric Composite Pr Materialsmentioning

confidence: 94%

Development of fully functionalized photorefractive polymers

Wang

2000

Macromol. Rapid Commun.

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In this article, we review recent progress in the area of photorefractive polymers. Photorefractive (PR) polymers are multifunctional materials which combine photoconductivity and electro‐optic response to show a new phenomenon: light‐induced reversible modulation of the refractive index. Because of their multifunctional features, design, synthesis and preparation of these materials exhibiting high performance is an intellectual challenge. Moreover, numerous applications of photorefractive materials in optical devices have been established using inorganic materials. Utilizing the unique features of organic polymeric materials to prepare useful devices is an engineering challenge. In the past several years, research in this area has gained momentum because numerous new materials which possess better characteristic photorefractive parameters than their inorganic counterparts have been synthesized. Several interesting devices have been presented. Two different approaches have been developed to synthesize and prepare PR polymers, namely composite materials and fully functionalized polymers. Both approaches have had success in identifying new materials and in gaining understanding of the design principles of better materials. This paper discusses these aspects and gives a prospective view about this field.

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“…A description of two-and four-wave mixing experiments are given in Sections 7.2.3 and 7.2.4, respectively. PSX, fi rst introduced as a PR host material by Zobel, [ 80 ] and its derivatives (arylamine-derivative PhPA ( 5d ) and hydrazone-derivative IDEH ( 5c ), [ 67 ] PSX-bTPA ( 5b ) [ 66 ] ), are by the nature of the dopant mixed into the polymer, as well as the dopant content (which in the case of guest-host materials may exceed 50 weight% of the composite) due to the increase of positional disorder induced broadening of the DOS. [ 60 ] As a rule of thumb, the mobility decreases as the concentration of charge-transport moieties decreases and the polarity and concentration of the dopant increases.…”

Section: Chemical Approaches To the Photorefractive Effect In Organicmentioning

confidence: 99%

“…The vast majority of guest-host PPCs in the literature are based on carbazolecontaining polymers like poly-(N-vinylcarbazole) [ 62 ] (PVK ( 1 ), sometimes denoted as PVCz) and polysiloxanes (PSX 5a ), [ 80 ] the former being a well studied system for applications in xerography [ 81 ] and commercially available. Throughout the 90s, PVK-based PR composites formed the dominant system, producing milestone materials like the fi rst polymeric material to show net gain, [ 82 ] complete internal diffraction effi ciency, [ 62 ] the fi rst demonstration of millisecond response times [ 46 ] and a huge variety of applications based on these materials (novelty fi ltering, [ 83 ] image amplifi cation, [ 84 ] optical correlation, [ 85 ] imaging through scattering media, [ 86 ] vibration analysis, [ 87 ] self-pumped phase conjugation, [ 88 ] amongst others).…”

Section: Chemical Approaches To the Photorefractive Effect In Organicmentioning

confidence: 99%

Organic Photorefractive Materials and Applications

2011

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This review describes recent advances and applications in the field of organic photorefractive materials, an interesting area in the field of organic electronics and promising candidate for various aspects of photonic applications. We describe the current state of knowledge about the processes involved in the formation of photorefractive gratings in organic materials and focus on the chemical and photo‐physical aspects of the material structures employed in low glass‐transition temperature amorphous composites and organic photorefractive glasses. State‐of‐the art materials are highlighted and recent demonstrations of photonic applications relying on the reversible holographic nature of the photorefractive materials are discussed.

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A polysiloxane‐based photorefractive polymer with high optical gain and diffraction efficiency*

Cited by 70 publications

References 18 publications

Undoped Photorefractive Ferroelectric Liquid Crystal

Undoped Photorefractive Ferroelectric Liquid Crystal

Development of fully functionalized photorefractive polymers

Organic Photorefractive Materials and Applications

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