Temperature influence on optical power spectrum of the tapered fiber device with a liquid crystal cladding

Abstract

This study presents the influence of temperature and electric field on optical power spectrum of an optical fiber taper device coated with nematic liquid crystal. The fiber-optic device consists tapered fiber placed between two glass electrodes covered with alignment layer and ITO. The tapering process caused the elongation of the optical fiber equal to 20.20 ± 0.16 mm and the taper waist diameter equal to 12 ± 0.5 μm. The applied tapered fiber is characterized by losses lower than 0.5 dB in the whole investigated spectrum range. The device was filled with nematic liquid crystal mixture E7 which is designed for an electric as well as temperature control of electromagnetic wave propagation. The measurements were performed for three kinds of initial liquid crystal molecules’ orientation (parallel, orthogonal and twist) in relation to the light beam propagating in the taper as well as axis of fiber. The induced reorientation of liquid crystal molecules was measured for visible and near infrared wavelength range [500-900 nm] at electric field range of 0–160 V and the temperature range of 20-60 °C. The relation between temperature and optical power spectrum of investigated fibers has been established.