Tunable Wavelength Filter based on Liquid Crystal Resonant Devices for Optical Communication Systems

The utilization of tunable wavelengths offers a broad spectrum of applications within optical communication systems. This study delves into the analysis of a micro ring resonator (MRR) and waveguide Bragg grating (WBG) employing the electro-optic effect to create a tunable wavelength filter. The analysis involves the use of transfer matrices for the ring resonator and coupled mode theory for the Bragg grating. By applying an electric field to these devices, changes in their optical properties are observed, leading to shifts in resonant wavelengths. The change in orientation of liquid crystal (LC) molecules results in different wavelength shifts observed in optical devices. Specifically, a $1 \mathrm{~nm}$ shift is observed for the grating, while a larger shift of $30 \mathrm{~nm}$ is observed for the ring resonator. These shifts reflect the sensitivity of these devices to variations in LCs’ molecular alignment, highlighting their potential for applications requiring precise control and tuning of optical properties.