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.
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 paper we present the theoretical and experimental analysis of the micro-electrodes system for the for dynamic change of the electric field direction. The system consists of four micro-electrodes introduced into the micro-holes and one rectangular air hole in the center and can applied for electric field sensing with polymer-based micro-structured optical fibers infiltrated with liquid crystals.
In this paper the photonic crystal fibers (PCFs) with various solid core diameters are presented. The attenuation obtained in the photonic band gap (PBG) mechanism for 37 rods forming the core of PLCFs was 0.16 dB/cm, which is the lowest attenuation reported to date. Reducing the fiber core diameter causes the increase of light penetration in fiber holes, which results in increased losses. The solid core of PCFs structure used in experiment consisted of 1, 7, 19 and 37 rods. The attenuation of PLCFs was measured by using the cut-back technique.
In great majority of the previous works devoted to photonic liquid crystal fibers (PLCFs) a photonic band-gap
propagation was investigated, since silica glass fibers' refractive index is lower than refractive indices of the most of
liquid crystals. In this work we focus on the electrical tuning of the index-guiding PLCFs based on host-fibers made from
multi-component glasses with enhanced value of refractive index. Impact of the electric field on the light propagation in
index-guiding PLCFs has been carefully studied and effective tuning of the phase birefringence, attenuation and
polarization dependent losses has been observed experimentally.
Photonic liquid crystal fibers (PLCFs) can be categorized in two principal groups: index guiding PLCFs and photonic
bandgap PLCFs. In this paper we focus on index guiding PLCFs in which effective refractive index of the
micro-structured cladding filled with liquid crystal is lower than refractive index of the fiber core. In such fibers
broadband propagation of light is observed and also effective tuning of guiding properties is possible (i.e. birefringence,
polarization dependent losses or attenuation tuning). Such fibers could be used for dynamic control of light in various
fiber optics systems, including optical fiber sensing setups.
Liquid Crystal Photonic Crystal Fibers (LC-PCFs) known also as Photonic Liquid Crystal Fibers (PLCFs) are advanced
specialty fibers that benefit from a combination of "passive" photonic crystal fiber host microstructures infiltrated with
"active" liquid crystal guest materials and are responsible for a diversity of new and uncommon spectral, propagation,
and polarization properties. This combination has simultaneously reinvigorated research 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 optical waveguides that utilizes unique guiding
properties of the micro-structured photonic crystal fibers and attractive tunable properties of liquid crystals. Comparing
to the conventional photonic crystal fibers, the photonic liquid crystal fibers can demonstrate greatly improved control
over their optical properties.
The paper describes basic physics including guiding mechanisms, spectral properties, polarization phenomena, thermal,
electrical and optical controlling effects as well as innovative emerging technology behind these developments. Some
examples of novel LC-PCFs highly tunable photonic devices as: attenuators, broadband filters, polarizers, waveplates,
and phase shifters recently demonstrated at the Warsaw University of Technology are also presented. Current research
progress in the field indicates that a new class of emerging liquid crystals tunable photonics devices could be expected.
In this work we present experimental results of the influence of hydrostatic pressure on polarization and propagation properties of the photonic crystal fibers infiltrated with liquid crystals. Two ranges of Photonic Band Gaps (PBGs) were observed and hydrostatic pressure was found to narrow the PBGs and also to introduce changes in the state of polarization The results obtained suggest great potential of the LC-infiltrated photonic crystal fibers for prospective constructions of fiber optics pressure sensors.
Photonic Crystal Fibers, optical fibers with regular structure of micro-holes running along the axial direction, have
ability to change their optical properties through inserting different materials into their holes. The paper presents our
latest experimental results of the influence of external electric field and hydrostatic pressure on propagation properties of
the photonic crystal fibers infiltrated with liquid crystals clearly indicating great potential for electric field and
hydrostatic pressure sensing applications. Operating range of both electric field and hydrostatic pressure sensors can be
tailored by different combination of a host photonic crystal fiber and a liquid crystal used for infiltration. Moreover, by
changing the operating wavelength different sensor responses can be obtained.