Mode analysis of a tunable side-polished optical fiber filter by a polymer-dispersed liquid crystal based on coupled-mode theory

A method for obtaining the mode characteristics of a tunable filter by a polymer-dispersed liquid crystal (TSFP) is presented, where the optical characteristics are analyzed using the coupled-mode theory. The TSFP is modeled as a fiber-to-planar waveguide (PWG) coupler with 4 layers, including a fiber cladding layer, a polymer-dispersed liquid crystal (PDLC) as a buffer layer, a PWG layer, and overlay layer. When applied to a 3-layer waveguide without a buffer layer, the proposed model gave more. exact solutions for the TSFP. The coupling is easily tuned by rising the heat of the electrode. and more occurred for the buffer layer with a higher index of refraction.