Research

Photonic liquid crystal fibers (PLCFs), a new class of highly-tunable photonic structures, possess unique optical properties resulting from the special infiltration of PCF air-holes with liquid crystalline material. Light guiding dynamics, including switching between different mechanisms of propagation (i.e. mTIR and PBG), can be simply achieved in PLCFs thanks to unique properties of an infiltrating substance. It is possible due to high electro-, magneto- and thermo-optic responses of LCs, while their refractive indices may be relatively easily changed either by temperature or external physical fields.

In this project we set the main goal towards investigation of the extended features of the new class of highly-tunable PLCF-based devices, and mainly to investigate their nonlinear properties. While nonlinear applications of PCFs are commonly known (e.g. they are commercially used for supercontinuum generation), nonlinear phenomena in PLCFs remain mainly uncovered. This project proposal was prepared in order to fill a gap in the research activities related to PLCF-based devices, while their characteristics and dynamics were tested for low optical powers only.

The proposed project, with interdisciplinary aspects, is merging together different fields of expertise and involving different branches of science including physics, optoelectronis/photonics, chemistry, and micro- and nano-technology.

It is well known that PCFs themselves are good candidates for new photonic devices. But when combined with LCs, and thus creating PLCFs may exhibit even greater advantages towards novel sensitive, tunable and efficient devices. However, implementation of such devices in practice still requires substantial scientific afford in terms of optimization, as well as predictions of their operation under different conditions (including predictions what happens when high power sources of light will be applied). One of them includes studies of the influence of nonlinear light propagation on functionality of the PLCF-based devices. Better understanding of changes in optical and tuning properties in an additional presence of high-power light excitation in such devices is needed and is one of the main goals of this project. Full theoretical analyzes and experimental investigations planned will allow for separation of the effects induced by nonlinearity itself from these present only for low optical powers.

By using laser sources (even with miliwatts of power), it turns out very often that nonlinear effects in liquid crystal take place, influencing thus light propagation effects in PLCFs. This project aims to analyze this particular problem, taking also advantage of creating novel innovative microstructred devices basing on implementation of nonlinear phenomena in PLCFs. For this purpose new numerical procedures for the PLCFs modeling will be developed, photonic devices of particular characteristics will be designed and eventually fabricated basing on the customized components. This project will cover a gap in the research activities performed in the Optics and Photonics Group, where only linear properties of PLCF-based devices have been intensively investigated so far. It will also allow to increase number of potential applications of the created highly-tunable PLCFs-based devices thanks to unique nonlinear properties of LCs used here as a guest material. It is know that beside electrically- and thermally-induced changes, one possibility to control the optical properties of LCs is launching a high-power light beam inducing changes in refractive indices of LCs (thanks to different mechanisms of optical nonlinearity that in particular conditions can be relevant). So far, changes of optical properties of PLCFs by applying other external physical fields were considered, without checking if nonlinear process is involved in the observed effect.

The studies covered by this project may have an applicative potential. The proposed PLCF-based devices have already found many practical application and better understanding of all processes behind their operation may significantly improve their functionality. Considering the PLCF as a matrix of waveguide channels and discrete light propagation therein may also result in real devices for all-optical switching. Demonstration of spatio-temporal nonlinear effects in PLCFs will be also enthusiastically appreciated by the scientists.