Study of wet oxidized AlxGa1-xAs for integrated optics

An investigation of wet oxidized AlxGa1-xAs layers in integrated optical applications is reported. Refractive index and thickness shrinkage of wet oxidized AlxGa1-xAs layers are measured using spectroscopic ellipsometry. A Cauchy fit to the refractive index is found in the wavelength range between 0.3 and 1.6 μm. The refractive index at 1.55 μm is found to be 1.66±0.01 with little dispersion around 1.55 μm. Very low loss single-mode waveguides with metal electrodes showing very low polarization dependence of loss coefficient are fabricated using wet oxidized AlxGa1-xAs layers as upper cladding. Optical polarization splitters are also designed and fabricated from the same type of waveguides taking advantage of increased birefringence. Designs utilizing wet oxidized AlxGa1-xAs are compared with conventional designs using only compound semiconductor heterostructures.