<title>Simulation of optical SOI directional coupler with polymer cover</title>

Abstract

An optical directional waveguide coupler with polymer cover has been studied with silicon-on-insulator (SOI) structure consisting of a 1.5 micrometers thick silicon surface layer, a 0.4 micrometers buried-oxide layer, and a 1 micrometers polymer cover layer. The characteristics of rib waveguide, radial curvature of S- shaped waveguide, coupling length an gap distance of SOI directional waveguide coupler have been studied at wavelength 1.55 micrometers . Simulation with beam-propagation- method, we demonstrate that using polymer cover on SOI direcitonal waveguide coupler will reduce the coupling length, relax the gap distance constraint, even increase output optical field intensity efficiently. The optimal result of propagation loss of the straight waveguide and the S-shaped waveguide can be designed to be 0.1dB/cm, respectively. The maximum bending angle of S-shaped SOI waveguide with polymer cover can be designed up to 0.63 degrees. The simulation of optical SOI directional waveguide coupler with polymer cover shows promising result for achieving optical interconnections on Si optical electronic high speed devices.