Photo-Induced Orientation of Nematic Liquid Crystals in Microcapillaries

Chychłowski, Miłosz; Ertman, Sławomir; Tefelska, M.; Woliński, Tomasz R.; Nowinowski-Kruszelnicki, Edward; Yaroshchuk, O.

doi:10.12693/aphyspola.118.1100

Cited by 24 publications

(14 citation statements)

References 21 publications

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“…The experiments (whose results are discussed in the next Section) have been performed in PLCFs of the length vary− ing from 1 to 2 cm. It is worth to note that for a purpose of the PLCF samples infiltrated with 6CHBT LC and tested in experimental conditions, special procedure based on the photo−alignment (with use of SE−130 polymer) [40] allows introducing particular anchoring conditions on the capillar− ies walls -thus forcing specific -i.e., planar -orientation of LC molecules inside the air−channels. In this case an ordi− nary refractive index of LC can be considered for any direc− tion on linear polarization of the input laser beam.…”

Section: Methodsmentioning

confidence: 99%

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Tunability of discrete diffraction in photonic liquid crystal fibres

Rutkowska

Laudyn

Jung

2014

Opto-Electronics Review

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In this paper theoretical and experimental results regarding discrete light propagation in photonic liquid crystal fibres (PLCFs) are presented. Particular interest is focused on tunability of the beam guidance obtained due to the variation in either external temperature or optical power (with assumption of thermal nonlinearity taking place in liquid crystals). Highly tunable (discrete) diffraction and thermal self-(de)focusing are studied and tested in experimental conditions. Specifically, spatial light localization and/or delocalization due to the change in tuning parameters are demonstrated, with possibility of discrete spatial (gap) soliton propagation in particular conditions. Results of numerical simulations (performed for the Gaussian beams of different widths and wavelengths) have been compared to those from experimental tests performed in the PLCFs of interest. Owning to the limit of experimental means, direct qualitative comparison was not quite accessible. Nevertheless, a qualitative agreement between theoretical and experimental data (obtained in analogous conditions) has been achieved, suggesting a compact and widely-accessible platform for the study of tunable linear (and nonlinear) discrete light propagation in two-dimensional systems. Proposed photonic structures are of a great potential for all-optical beam shaping and switching.

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Section: Methodsmentioning

confidence: 99%

“…After introducing the liquid crystal into the air−channels of the host PCF, several molecular arrangements can be obtained (e.g., when proper orientation treatment is perfor− med [40] or/and under external fields and factors [18]) -see inset on the right−hand side of Fig. 1(b) for details.…”

Section: Definition Of Plcf Structurementioning

confidence: 99%

Tunability of discrete diffraction in photonic liquid crystal fibres

Rutkowska

Laudyn

Jung

2014

Opto-Electronics Review

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“…The pho− toalignment is seemed to be the unique method for this case, since the light is capable to reach the tubes passing through the glassy body of the PCF [14][15][16][17][18][19]. First attempts in this direction have been recently made [20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Liquid crystal alignment in cylindrical microcapillaries

Chychłowski

Yaroshchuk

Kravchuk

et al. 2012

Opto-Electronics Review

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A variety of alignment configurations of liquid crystals (LCs) inside the glassy cylindrical capillaries is realized by using alignment materials providing different anchoring. The radial configuration with central disclination line is obtained for homeotropic boundary conditions. In turn, the axial, transversal and tilted alignment structures are realized by using materials for planar anchoring. The uniformity and controlling of the latter structures were provided by photoalignment method. This approach can be further used to control LC alignment in the photonic crystal fibers recognized as advanced elements for different optical devices.

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“…In our early experiments, microstructured fibers were infiltrated with LCs by the capillary action just by immersing one end of the PCF in a container with an LC Emerging photonic devices based on photonic liquid crystal fibers [23][24][25]. Our approach is based on creation of a thin aligning film of a polymer inside each micro-hole.…”

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confidence: 99%

“…In next step, the fiber is heated for a while to evaporate the remains of the solvent. The last step depends on the type of the polymer used for aligning -thermal polymerization may be obtained by baking the sample, and photo-polymerization can be induced by irradiating it with ultra-violet (UV) light [23][24][25]. In practice, thermal polymerization is easier, so thermal-alignment is more repeatable than photoalignement, where careful and precise irradiation of the PCF is required.…”

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confidence: 99%

Emerging photonic devices based on photonic liquid crystal fibers

Woliński

Ertman

Budaszewski

et al. 2011

Photon. Lett. Poland

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Abstract-Photonic liquid crystal fibers (PLCFs) define a new class of optical waveguides that combines unique properties of microstructured photonic crystal fibers and liquid crystals. Current progress of research in the field of PLCFs means that a new class of emerging photonics devices can be expected, i.e. tunable attenuators, tunable broad-band filters, tunable polarizers (with an arbitrary PDL and a variable axis of polarization), tunable waveplates, and tunable phase shifters with high retardance will appear in the near future. In this work we would like to discuss this perspective, paying special attention to two most challenging technological issues such as control of LC molecules orientation and permanent connecting of PLCFs to standard fibers.Transmission properties of photonic crystal fibers (PCFs) can be tailored in a wide range by changing geometry of their microstructured cladding [1]. Generally, in the PCFs light can be guided by two different mechanisms: indexguiding (similar to the classical waveguide effect based on mTIR-modified total internal reflection) and the photonic band-gap (PBG) effect. The PBG propagation occurs when the effective refractive index of the microstructured cladding is higher than the refractive index of the core, and in this case only selected wavelengths can be guided [1]. Transmission properties of PCFs can be also arbitrarily changed by filling their micro-holes with various substances [2] and liquid crystals (LCs) belong to the most interesting materials for these applications due to the high sensitivities to external physical fields. The first paper on photonic liquid crystal fibers (PLCFs) has been published in 2003 [3]. Since that time there has been a continuous increase in the number of research groups working in the field, and thermal tuning of the photonic band-gap in the PLCFs has been shortly reported also by different authors [4][5][6] Electrical tuning in a hollow-core liquid-crystal photonic crystal fiber was demonstrated in 2004 [7] and also in silica glass-core photonic liquid crystals fibers [8][9]. In Ref.[9] thermal tuning of the PLCF guiding mechanism was presented by using a special lowbirefringence LC mixture with the ordinary refractive index lower (in a certain temperature range) than the refractive index of the silica glass. The efficiency of electrical tuning could be significantly improved by using dual-frequency liquid crystals [10][11] [11,[17][18][19] have been obtained in silica-based PCFs filled with LCs. Other interesting effects observed in the LC-PCFs were based on a PCF made of multi-component glasses, with increased value of the refractive index, so that index-guiding propagation was possible even after infiltration with LCs. In particular, low-loss propagation and continuously tunable birefringence was experimentally demonstrated [20].Recently, a number of prototype tunable devices based on PLCFs have been developed in our laboratory [21,22]. These devices include tunable attenuators, tunable broadband filters, tunable polarizers ...

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Photo-Induced Orientation of Nematic Liquid Crystals in Microcapillaries

Cited by 24 publications

References 21 publications

Tunability of discrete diffraction in photonic liquid crystal fibres

Tunability of discrete diffraction in photonic liquid crystal fibres

Liquid crystal alignment in cylindrical microcapillaries

Emerging photonic devices based on photonic liquid crystal fibers

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