Design and characterization of an out-of-plane polymer waveguide grating coupler

Abstract

A polymer waveguide grating coupler to vertically couple light between planar waveguide and fiber is proposed and designed. In order to estimate the coupling performance of the proposed coupler with curved and chirped grating, the diffraction characteristics of the waveguide grating with a uniform period as an in/out out-of-plane coupler are investigated. The coupling efficiency and coupling length exhibiting the diffraction characteristics of a uniform waveguide grating with various structure parameters are calculated based on Bloch-wave analysis. With the optimized structure parameters showing the high coupling performance, the overall coupling efficiency of the polymer waveguide grating coupler is obtained by introducing 2D Bloch-wave analysis-based local linear grating model. The calculated overall coupling efficiency of the coupler is determined to be approximately 30%.

One-step fabrication of polymer components for microphotonics by gray scale electron beam lithography

“…Typical grating output couplers giving high coupling efficiency include the shallow-etched grooves [4], metal lines [5], curved and chirped gratings [6] and slanted grooves [7]. Although most of these designs are based on a silicon-oninsulator (SOI) technique, they can be adopted to a polymer based platform with merely geometrical size modification.…”