Optical properties of selected photonic microstructures based on BP LCs doped with gold nanoparticles (Au NPs) are discussed. It has been shown that the examined photonic microstructures can provide promising tunable optical properties, simultaneously enhancing temperature stability of liquid crystalline microstructures. This is due to the presence of Au NPs with an appropriate organic coating in the LC matrix. It has been demonstrated that the investigated BP LC-based photonic microstructures seem to be very promising materials for realizing electro-optical modulation and switching as well tunable filter applications and sensing capabilities providing better transmission properties for perspective emerging tunable photonic devices.
Liquid crystals over the last two decades have been successfully used to infiltrate fiber-optic and photonic structures initially including hollow-core fibers and recently micro-structured photonic crystal fibers (PCFs). As a result photonic liquid crystal fibers (PLCFs) have been created as a new type of micro-structured fibers that benefit from a merge of “passive” PCF host structures with “active” LC guest materials and are responsible for diversity of new and uncommon spectral, propagation, and polarization properties. This combination has simultaneously boosted research activities in both fields of Liquid Crystals Photonics and Fiber Optics by demonstrating that optical fibers can be more “special” than previously thought. Simultaneously, photonic liquid crystal fibers create a new class of fiber-optic devices that utilize unique properties of the photonic crystal fibers and tunable properties of LCs. Compared to „classical” photonic crystal fibers, PLCFs can demonstrate greatly improved control over their optical properties. The paper discusses the latest advances in this field comprising PLCFs that are based on nanoparticles-doped LCs. Doping of LCs with nanoparticles has recently become a common method of improving their optical, magnetic, electrical, and physical properties. Such a combination of nanoparticles-based liquid crystals and photonic crystal fibers can be considered as a next milestone in developing a new class of fiber-based optofluidic systems.
In this communication we present our results on characterization of selected liquid crystalline materials in terms of their optical properties and their prospective applications as waveguiding layers in the integrated optic systems. Specifically, LCs refractive indices, with their dependence on temperature and within specific spectral range, have been measured and reported. The measurements were performed with use of the wedge-cell method. This simple goniometric technique is particularly useful when applied for liquid crystalline materials characterized by high refractive indices, for which refractometric methods are approaching their upper limits. It is important that the method proposed here requires relatively small amount of liquid crystalline material and gives reasonable results even if the light sources from the wide spectral range are applied. Experimental data allows for chromatic dispersion curves to be obtained by the numerical fitting with use of the Cauchy model.
Photonic crystal fibers (PCF) have been selectively filled with a cholesteric liquid crystal (ChLC) with special interest in
the blue phase (BP) of the liquid crystal. It has been observed thermal tuning of the guided light in the visible region. A
dramatically enhance appears when the phase of the liquid crystal changes from cholesteric to blue phase I (BPI). When
a thermal range of the blue phase I is achieved, no changes are observed while increasing temperature from BPI through
BPII and to the isotropic phase.
In this report, the results of theoretical analyses on the light guidance in the microstructured fibers infiltrated with liquid crystalline materials are presented. More precisely, the analyzed photonic structure is considered as 2D optical lattice (i.e., matrix of the mutually parallel waveguide channels) allowing thus the light to be switched (tunneled) between adjacent channels, as predicted by the series of the numerical simulations performed. The latter are based on the finite difference beam propagation method with the Crank-Nicholson scheme applied. It has been demonstrated that different scenarios for discrete light propagation can be obtained, depending on the internal and external factors governing geometrical and optical properties of both the light beam and the fiber. Our findings pave the way for all-optical switching to be successfully developed in the future practical photonic devices.
In this report, numerical analysis on light propagation in photonic crystal fibers infiltrated with liquid crystalline
materials is presented. In particular, influence of the optical power is shown, as obtained from numerical simulations
based on the finite difference beam propagation method.
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