Polarization Control in Graphene‐Based Polymer Waveguide Polarizer

Abstract

AbstractPolarizers have been intensively investigated theoretically and experimentally, with innovative device designs and emerging optical materials. However, the polarization state and extinction ratio in a waveguide polarizer are not changeable, owing to the passive device operation principles. In this study, a polarization‐switchable graphene waveguide polarizer based on the polarization‐dependent light absorption of graphene film of different thicknesses and micro‐opto‐mechanical systems (MOMS) technology is demonstrated. A superstrate on which graphene layers of different thicknesses are integrated is positioned on the optical waveguide core, and is mechanically pushed to suppress the unwanted polarization state. Graphene thickness on the superstrate plays a key role in switching the device's polarization state: A few‐layer graphene film on the superstrate attenuates the transverse‐electric (TE) mode, making the device transverse‐magnetic (TM) passing, while a many‐layer graphene diminishes the TM mode, making the device TE passing. The dynamic optical attenuation function is automatically configured via accurate and discrete mechanical adjustment of the air gap between the superstrate and the waveguide core. The theoretical simulation and the experimental result exhibit good agreement. This work introduces an idea for tuning the polarization state in a polarization diverse coherent optical system and may contribute to a wide range of applications in MOMS systems.