Huge birefringence in oxidized GaAs/AlAs optical waveguides for phase-matched nonlinear frequency conversion

Summary form only given. Large nonlinear coefficient, possibility of integration with semiconductor lasers, and excellent control of structures make GaAs waveguides very well suited to nonlinear frequency conversion in the near-infrared. Realization of GaAs waveguide converters has been prevented until now by the problem of phase matching. Phase matching can be achieved by use of artificial birefringence present in a multilayer structure. However, in the GaAs-AlAs system there is not enough index contrast. Recently, a wet oxidation technique was developed to selectively convert AlAs into an oxide with refractive index near 1.6. We propose use of this low index oxide to enhance birefringence in a GaAs-AlAs waveguide and obtain phase matching between TE and TM modes.