Vertically integrated optical directional couplers in glass for improved edge coupling to a thin-film photodetector

Abstract

An improved vertical coupling structure, consisting of a graded-index planar buried waveguide in glass and a dielectric overlayer, is designed and realized to provide an optimum edge coupling to a modelled GaAs photodetector. Calculations of the attenuation coefficient and coupling efficiency show an optimum absorption behavior. Normal mode measurements and beam propagation calculations of the coupling length and power transfer ratio are compared.