Andrzej W. Domanski

Influence of temperature and electrical fields on propagation properties of photonic liquid-crystal fibres

The paper reports temperature and external electrical field effects on propagation properties of a photonic liquid-crystal fibre composed of a solid-core photonic crystal fibre filled either with a prototype nematic liquid crystal characterized by extremely low (of the order of ~0.05) material birefringence or with a typical nematic pentylo-cyano-biphenyl, PCB (birefringence of the order of ~0.2). The nematic liquid crystal was introduced into the micro holes of the photonic crystal fibre by the capillary effect. Depending on the liquid crystal material introduced into the micro holes and due to anisotropic properties of the photonic liquid-crystal fibre, switching between different guiding mechanisms controlled by temperature and an external electric field has been demonstrated. This creates great potential in fibre optic sensing and optical processing application.

Influence of high hydrostatic pressure on beat length in highly birefringent single-mode bow tie fibers

New experimental studies on the effects of high hydrostatic pressure on highly birefringent optical fibers are presented. Using Rayleigh scattering, the effect of beat length modification in highly birefringent singlemode bow tie fibers under high pressure up to 100 MPa was investigated. The results indicate that the beat length decreases with pressure, with the mean coefficient of 1/L(B0)|dL(B)/dp| = 0.15%/MPa. A similar decrease of beat length was observed when uniaxial longitudinal stress was applied to the bow tie fiber. A more developed semiphenomenological interpretation of these experimental results is also presented in the paper.

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.

Polarization Optics of Microstructured Liquid Crystal Fibers

The present paper discusses polarization phenomena occurring in microstructrured liquid crystal fibers and in particular solid-core photonic crystal fibers infiltrated with liquid crystals. We report on the latest experimental polarization characteristics of microstructured photonic crystal fibers filled with prototype nematic liquid crystal guest materials characterized by either extremely low (of the order ∼ 0.05) or medium (of the order ∼ 0.2) material birefringence. Due to anisotropic properties of the microstructrured liquid crystal fibers switching between different guiding mechanisms as well as electrically and temperature-induced tuning of light propagation have been demonstrated. These preliminary results hold great potential for both fiber-optic sensing and in-fiber polarization mode dispersion control and compensation.

Depolarization of partially coherent light in liquid crystals

In the paper we present results of analysis of partially coherent light depolarization in two types of liquid crystals possessing linear birefringence controlled by temperature and external electric field changes. Some experimental results of degree of polarization measurements for different light sources as a superluminescent diode and a laser diode are also presented.

Surface roughness measurement with optical fibers

A method of surface roughness measurement utilizing polarization-maintaining optical fibers is presented. The method, which is based on polarization changes in light scattered from the measured rough surface, is compared with intensity-based fiber-optic surface roughness measurement and correlated with some parameters. For intensity-based measurement, a three-branch optical fiber cable is used in which two branches are coupled to two different sources. It is concluded that the uncomplicated fiber-optic method with its compact, flexible, remote-controllable setup, allows differentiation of surface roughnesses in the range of 0.5-30.0 mu m (R/sub q/) based on measurement either of intensity or of the degree of polarization of light scattered from the rough surface. >

A Photonic Crystal Fiber and Fiber Bragg Grating-Based Hybrid Fiber-Optic Sensor System

A hybrid sensor that operates in the intensity domain by converting the polarization and wavelength information from the photonic crystal fiber sensor and fiber Bragg grating (FBG) sensor, respectively, into intensity variation is presented in this paper. The hybrid fiber-optic sensor system involves a combination of a polarimetric sensor based on a photonic crystal fiber and a FBG sensor and is used for simultaneous strain and temperature measurement. The strain sensitivity of the polarization maintaining photonic crystal fiber at different lengths and the corresponding slope required for the edge filter which converts the FBG wavelength information into intensity are studied and presented in this paper. The proposed sensor configuration has a wide range of applications in smart fiber-optic sensing.

Temperature tuning of polarization mode dispersion in single-core and two-core photonic liquid crystal fibers

In this paper we present numerical and experimental results of propagation and polarization properties of the photonic liquid crystal fibers (PLCFs) in which only selected micro holes were filled with nematic liquid crystal (LC) guest materials. As a host photonic crystal fiber (PCF) structure, we used a commercially available highly birefringent PCF (Blazephotonics, UK). A tunable laser operated at infrared has powered the PLCFs under investigation infiltrated by the 1550 nematic LC synthesized at the Military University of Technology. Temperature induced changes of the polarization mode dispersion (PMD) as well switching between fundamental and higher order modes and also single-core and two-core propagation were successfully demonstrated.