All-optical control of discrete light propagation in photonic liquid crystal fibers

Summary form only given. Over the last decade, photonic liquid crystal fibers, PLCFs [which are formed of photonic crystal fibers (PCFs) infiltrated with liquid crystals (LCs)] are subjected to intense scientific investigations. Unique characteristics of the host structures and guest materials translate into the special properties of PLCFs. In fact, LCs used as inclusions allows the optical parameters of PLCFs to be dynamically adjusted by external fields and factors (e.g. by electric and magnetic fields, temperature, strain and pressure) [1] and/or by light beams themselves (i.e. when nonlinear effects are considered in LCs) [2].In this work, the results of theoretical studies and experimental tests on the light propagation in PLCFs are presented. While refractive index of typical LC is higher than that of silica glass, analyzed photonic structure can be considered as a matrix of mutually parallel waveguide channels. This connotes discrete light propagation [3] to be observed in PLCFs, with the output beam profile strongly dependent on geometrical and optical properties of both the beam (i.e. its wavelength and size) and the fiber (i.e. its periodicity and index contrast). Importantly, discrete light propagation in PLCFs can be tuned dynamically - not only by external fields and factors but also, what is particularly important in the context of this communication, by varying optical power of the signal optical beam. As it is shown by numerical simulations, when optical nonlinearity is considered, spatial light localization and/or delocalization can be obtained with the final scenario dependent on the optical power level and the molecular orientation and reorientation of LC (see Fig. 1b-c). Under particular conditions, discrete spatial soliton can be obtained, paving thus the way for all-optical switching to be obtained in PLCFs. Experimental data, acquired with use of the signal beam from Ti:Sapphire laser, also confirm a powerdependence of the beam profile at the- output facet of PLCF. A weak collinear probe at the different wavelength was also applied to monitor how the single waveguide channel is decoupled from the rest of the matrix.