Aleksandra Czapla

Polarization effects in photonic liquid crystal fibers

In this paper we present experimental results of polarization properties of photonic liquid crystal fibers, also with permanent anisotropy achieved by using photo-aligning layers within the micro holes. Single-polarization propagation has been demonstrated in three ways: either by application of an external electric field, by using special aligning layers or by using an anisotropic host—commercially available highly birefringent Blazephotonics photonic crystal fiber infiltrated with liquid crystals. The possibility of thermal birefringence tuning in photonic liquid crystal fibers by using low-birefringence liquid crystals is also presented.

Photonic Liquid Crystal Fibers for Sensing Applications

The paper presents our latest experimental results on the influence of temperature, an external electric field, and hydrostatic pressure on propagation properties of the photonic crystal fibers infiltrated with liquid crystals of low and medium material anisotropies. Measurand-induced shifts of the photonic bandgap wavelengths give information about the value of temperature, voltage, and pressure. Moreover, temperature-dependent positions of the photonic bandgap wavelengths in the transmission spectrum can serve to determine the thermal characteristics of the liquid crystal ordinary refractive index.

Photonic liquid crystal fibers : a new challenge for fiber optics and liquid crystals photonics

The paper reviews and discusses the latest developments in the field of the photonic liquid crystal fibers that have occurred for the last three years in view of new challenges for both fiber optics and liquid crystal photonics. In particular, we present the latest experimental results on electrically induced birefringence in photonic liquid crystal fibers and discuss possibilities and directions of future developments.

Liquid crystal molecular orientation in photonic liquid crystal fibers with photopolymer layers

Photonic liquid crystal fibers (PLCFs) combine unique properties of photonic crystal fibers and liquid crystals (LCs). Liquid crystal molecules orientation within the PLCFs has crucial impact on their optical properties since it determines the radial refractive index profile of the LC-filled micro-holes. There are many techniques used for LC molecules orientation control, but most of them are not suitable for application in microstructured fibers characterized by holes with diameters in the order of few micrometers. It seems that the only method that could be applied in PLCFs is using of thin photopolymer layers, in which surface anisotropy can be induced in the way of photochemical reactions. In this paper we present preliminary experimental results of the photoinduced molecular alignment in the PLCF induced by a thin polyvinylcinnamate (PVCi) film irradiated with the linearly polarized ultraviolet light.

Light propagation in highly birefringent photonic liquid crystal fibers

Photonic liquid crystal fibers have already been demonstrated as a promising perspective for creation of new classes of dynamically tunable optical fiber devices. By combining different geometries of photonic crystal fibers with a variety of different liquid crystals it is possible to obtain a new generation of fibers with dynamically tunable properties, e.g., transmission spectra, attenuation or dispersion.In this paper, tunable birefringence in a commercially available highly birefringent Blazephotonics PM-1550-01 photonic crystal fiber selectively filled with a low birefringence liquid crystal has been experimentally demonstrated. Theses experimental results have been compared with simulations based on the multipole method.

Tuning Cladding-Mode Propagation Mechanisms in Liquid Crystal Long-Period Fiber Gratings

This paper presents the latest developments in the field of liquid crystal long-period fiber gratings (LC-LPFGs). The new design of LC-LPFG proposed here has unique propagation properties stemming from the use of special low-birefringence LC mixtures as an “active” external layer on the LPFG. In specific temperature regions, the refractive indices of these LC mixtures are below the refractive index of fused silica. This feature makes it possible to dynamically control the propagation mechanisms of the cladding modes. As a result, a high-efficiency thermal and/or electric tuning of LC-LPFGs could be achieved.

Long-Period Fiber Gratings with Low-Birefringence Liquid Crystal

The paper presents a long-period fiber grating (LPFG) with a unique liquid crystal (LC) cladding. We report the results of experiments on the LPFGs spectral properties that can be modified by temperature due to the presence of a low-birefringence nematic LC mixture. We also present our latest results concerning the influence of an external electric field on an LPFG with a medium-birefringence LC. The LPFGs are fabricated by using electric arc discharges in two types of fiber: single-mode (SM) fibers and photonic crystal fibers (PCFs). The experimental study is focused on achieving external tuning by adjusting thermal and electric field effects influencing the spectral properties of LPFGs using LCs.

Polarizing and Depolarizing Optical Effects in Photonic Liquid Crystal Fibers

The paper describes polarization phenomena occurring in photonic crystal fibers infiltrated with liquid crystals and presents latest experimental results of the influence of temperature, external electric field and hydrostatic pressure on their polarization properties. Also depolarization effects in photonic liquid crystal fiber induced by an external electric field are brought forward.

Improving the electric field sensing capabilities of the long-period fiber grating coated with a liquid crystal layer

The hybrid liquid crystal long-period fiber grating structure presented here uses the 1702 liquid crystal as a thin layer on the bare long-period fiber grating. To achieve the highest long-period fiber grating sensitivity to the liquid crystal layer presence, a UV-induced host grating, with a relatively short period of 226.8 μm, was chosen. This design makes it possible to couple light from the propagating core mode to a cladding mode at a wavelength near the phase-matching turning point. This phenomenon is exploited here for the first time to measure the thermal and electric field responses of the liquid crystal long-period fiber grating structure. All experimental results achieved in this work are supported by theoretical analysis.

Depolarization of light in microstructured fibers filled with liquid crystals

In the paper we analyze microstructured optical fibers filled with typical nematic liquid crystals, i.e., 5CB and 6CHBT under influence of external electric field or temperature. We use the modified Mueller matrix method with an additional depolarization matrix to calculate degree of polarization changes of the light propagating in the liquid-crystal infiltrated microstructured optical fibers. Preliminary experimental results of light depolarization measurements during propagation in these microstructured fibers are also presented.