Wavelength Tunable Operation in Si Waveguide Grating That Has a Ferroelectric Liquid Crystal Cladding

We obtained the wavelength selective operation in a grating Si rib waveguide that has an ferroelectric liquid crystal (FLC) cladding. The FLC cladding gives a phase shift change for the traveling lightwave in the waveguide in accordance with the polarity of the applied voltage. We propose the wavelength selective filter using this operation and demonstrate the selective switching and the tunable operation of our fabricated device. We also report its time response and dependence on the applied voltage and propose a new operating method to achieve a continuous phase change by using the FLC layer that has binary characteristics.