Optical properties of AlxGa1-xAs heterostructure native oxide planar waveguides

We have used prism coupling measurements to study the Al dependence of the refractive index in wet thermal native oxides of Al _xGa_1-xAs for Al compositions x=0.3 to 0.97, and found that a suitable index variation (Δn⩾0.06 for x=0.4 to 0.8) exists for achieving waveguiding within the native oxide layers themselves. Native oxide planar waveguides are fabricated by fully oxidizing AlGaAs semiconductor heterostructures. By enabling waveguiding within AlGaAs native oxides, the large propagation distance allows the characterization of spectral absorption and interface scattering loss mechanisms not readily measured via thin film transmission measurements. We present loss measurement data on a multimode two-layer (single heterostructure) waveguide