Electro-Steering Tapered Fiber-Optic Device with Liquid Crystal Cladding

The paper presents the results of design, manufacturing, and characterization of a hybrid broad band in-line fiber-optic device. It uses nematic liquid crystal as cladding with electro-steering properties in a biconical optical fiber taper structure. Liquid crystal mixtures denoted as 6CHBT and E7 are designed for electric as well as temperature control of electromagnetic wave propagation in a broad wavelength range. The applied taper with 10±0.5 μm diameters has losses lower than 0.5 dB in whole investigated spectrum range. Three kinds of initial liquid crystal molecules’ orientations (parallel, orthogonal, and twist) in relation to the light beam propagating in a taper were applied. The performance of a tuned cladding was studied at an electric field of the range of 0–190 V and the temperature range from 20°C up to 42°C and 59°C for 6CHBT and E7, respectively. The induced reorientation of liquid crystal molecules was measured at a broad wavelength range (550-1550 nm).

Multiple Light Coupling and Routing via a Microspherical Resonator Integrated in a T-Shaped Optical Fiber Configuration System

We demonstrate a three-port, light guiding and routing T-shaped configuration based on the combination of whispering gallery modes (WGMs) and micro-structured optical fibers (MOFs). This system includes a single mode optical fiber taper (SOFT), a slightly tapered MOF and a BaTiO3 microsphere for efficient light coupling and routing between these two optical fibers. The BaTiO3 glass microsphere is semi-immersed into one of the hollow capillaries of the MOF taper, while the single mode optical fiber taper is placed perpendicularly to the latter and in contact with the equatorial region of the microsphere. Experimental results are presented for different excitation and reading conditions through the WGM microspherical resonator, namely, through single mode optical fiber taper or the MOF. The experimental results indicate that light coupling between the MOF and the single mode optical fiber taper is facilitated at specific wavelengths, supported by the light localization characteristics of the BaTiO3 glass microsphere, with spectral Q-factors varying between 4.5 × 103 and 6.1 × 103, depending on the port and parity excitation.