Resonance coupled optical coupler with semiconductor waveguide layer

Abstract

An electro-optic coupler made of consecutively deposited layers of semiconductor material has an one waveguide layer a multiple-quantum-well structure which exhibits a strong index of refraction dispersion in response to an electric field. Another waveguide layer separated from the multiple-quantum-well structure by a coupling layer is made of a bulk semiconductor material having an index of refraction which is comparatively unaffected by the electric field and which is substantially equal to one of the values of the index of refraction that the quantum well structure can assume. Resonant coupling of the waveguide layers is affected by a uniform electric field generated by a voltage applied between metalization on a confinement layer covering the top waveguide and a substrate on which the waveguide layers and coupling layer are grown over a lower confinement layer. When the indices of refraction of the two waveguides are equal, light injected into one waveguide is switched to the other. On the other hand, when the indices of refraction of the two waveguides are not equal, a parallel propagation condition exists. The coupler can be used either as a switch or an attenuator.