Abstract

New integrated optical modulator designs are presented that are based on a GaAs-clad dielectric waveguide technology. These devices exhibit unique features that arise due to the periodic coupling between the propagating lossless guided modes of a dielectric optical waveguide and the lossy modes supported by a semiconductor cladding layer. An incident light beam that propagates with a photon energy above the band gap of the GaAs introduces carriers that shift the absorption of the GaAs cladding. The carriers induce shifts in the periodic interaction between the modes of the dielectric portion of the waveguide and those of the GaAs cladding. Depending on the cladding thickness and material absorptions that are used, the induced shifts can modulate either the amplitude or phase of a guided lightwave that propagates at a photon energy near the band gap of the GaAs. The coupling properties of the clad-waveguide structure and the effects of shifts in the GaAs cladding permittivities are evaluated analytically. Proposed device structures will allow the use of a dielectric waveguide and a thin isolated GaAs layer with a GaAs substrate so the modulator will be fully integrable with other guided-wave devices.

© 1985 Optical Society of America