Loss-reduced photonic liquid-crystal fiber by using photoalignment method

Chen, Ching-Hsiang; Lee, Chun-Hong; Lin, Tsung‐Hsien

doi:10.1364/ao.49.004846

Cited by 14 publications

(2 citation statements)

References 16 publications

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“…Before filling with the respective FLC, the capillaries were prepared to promote parallel LC alignment. Because the inner surfaces of the cavity were not available for mechanical treatment, it was necessary to use treatment of photosensitive compounds (either polymer precursors or azo dyes) with linearly polarized radiation for this purpose. − Previous experiments indicated that this nonintrusive method works well for capillaries and optical fibers. ,− Here, we used the azo dye brilliant yellow (BY) and applied a method described by Ertman and co-workers . For this purpose, a solution of 2% BY in hexane was filled into the capillary, the sample was heated to 140 °C for 20 min, and then excess solution was removed under a nitrogen stream of approximately 2 bar.…”

Section: Experimental Methodsmentioning

confidence: 99%

Ferroelectric Liquid Crystals in Microcapillaries: Observation of Different Electro-optic Switching Mechanisms

2017

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Ferroelectric liquid crystals (FLCs) can provide fast electro-optic switching effects in photonic crystal fibers, which are promising for developing integrated optical modulators to be used for optical telecommunication. The present study describes experiments on capillaries filled with FLCs, which pave the way toward application of FLCs in state-of-the-art solid core microstructured optical fibers. A method to achieve uniform alignment of the helix axis and the appearance of two different switching modes with switching times in the submillisecond range are found. An additional slow relaxation that was reported recently can be attributed to space charge fields, which may appear due to the migration of ions.

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Section: Experimental Methodsmentioning

confidence: 99%

Ferroelectric Liquid Crystals in Microcapillaries: Observation of Different Electro-optic Switching Mechanisms

2017

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“…As displayed in Fig. 11.2, it has been successfully applied to align LCs in photonic crystal fibers so as to reduce scattering loss and improve their optical performance [61,62]. LC configuration can be controlled by varying the photoirradiation.…”

Section: Bulk-mediated Photo-isomerization and Adsorption Effectsmentioning

confidence: 99%

Photo-Alignment Technology

Lin

2014

Topics in Applied Physics

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LCDs are used in many everyday devices, including mobile phones, notebook computers and wide screen televisions. A typical LCD is composed of two glass substrates between which is a gap that is filled with LC. The arrangement of the LC is controlled by the boundary condition of an alignment film. A long-range orientational interaction causes the preferable alignment of a LC by the surface boundary to extend into the LC bulk. The alignment layer is typically rubbed with a special cloth to induce a unidirectional alignment of the LC. In the first devices based on twisted LCs, these LCs were aligned only by rubbing transparent electrodes. The rubbing technique became much more reliable when the glass substrate was covered with a rubbed polymer layer. The rubbing of polymers is a very simple technique and it is now extensively utilized in both small scientific laboratories and large LCD factories.Despite the extensive use of rubbing in LCD manufacturing, it has some serious shortcomings that arise from the contact involved in rubbing. These critically affect the production of the most recent generation of LCDs and miniature LC photonic devices. First, rotational rubbing for the polymer surface causes the accumulation of static charges and the formation of fine dust particles. The accumulation of static electricity may destroy the transistors or diodes in the LCD. The second shortcoming is the effect of decreasing in manufacturing yield. Rubbing for large and high-resolution active matrix LCDs (AMLCDs) involve additional difficulties that are associated with the precise control of the rubbing characteristics. Other problems are the difficulty of producing local structures with the required LC director alignment in the selected areas of the device. Finally, this method cannot be used to align LCs in closed volumes.For all of the above reasons, new alignment solutions and approaches are sought. There are some alternative methods of rubbing include laser writing, micro-rubbing, ion beam irradiation and photoalignment. Of these methods, the

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Photonic Micro‐ and Nanostructures, Metamaterials

Kitzerow

2014

Handbook of Liquid Crystals

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Periodic structures with feature sizes comparable to the wavelength of electromagnetic radiation (“photonic crystals”) or feature sizes much smaller than the considered wavelength (“metamaterials”) can have unique optical properties, including ‐ for example ‐ unusual transmission, reflection, and diffraction, enhanced or inhibited transmission of emitters embedded in these structures, or zero and even negative refraction, which offer many opportunities for integrated optics and photonics. This topical field may benefit from liquid crystals in two ways: A mesophase with an intrinsic periodic structure may behave as a natural, self‐organized material of this kind or serve as a template for producing such materials. An artificial structure can be equipped with tunable optical properties by infiltration with liquid crystals owing to their optical nonlinearity or the sensitivity of their dielectric permittivity to external controlling parameters. This chapter gives an overview of the latter type of photonic crystals (including microstructured fibers) and metamaterials. Emerging concepts of possible applications for tunable light sources, integrated tunable filters or switchable optical components, and optical sensors are summarized.

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Loss-reduced photonic liquid-crystal fiber by using photoalignment method

Cited by 14 publications

References 16 publications

Ferroelectric Liquid Crystals in Microcapillaries: Observation of Different Electro-optic Switching Mechanisms

Ferroelectric Liquid Crystals in Microcapillaries: Observation of Different Electro-optic Switching Mechanisms

Photo-Alignment Technology

Photonic Micro‐ and Nanostructures, Metamaterials

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