Low-loss buried AlGaAs/AlOx waveguides using a quasi-planar process

In this paper, we demonstrate that buried oxide-confined waveguides can be formed using a lateral oxidation process carried out through a discrete set of small-diameter via-holes instead of the conventional scheme where the oxidation starts from the edges of etched mesas. The via-hole oxidation is shown to lead to straight waveguides with smooth oxide/semiconductor interfaces and whose propagation losses are similar to one obtained using the standard process but with the advantage of maintaining a quasi-planar wafer surface. It thereby paves the way towards a simplification of the fabrication of III-V-semiconductor-oxide photonic devices.