A study of wet oxidized Al/sub x/Ga/sub 1-x/As for integrated optics

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Abstract
An investigation of wet oxidized Al/sub x/Ga/sub 1-x/As layers in integrated optical applications is reported. Refractive index and thickness shrinkage of wet oxidized Al/sub x/Ga/sub 1-x/As 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 /spl mu/m. The refractive index at 1.55 /spl mu/m is found to be 1.66/spl plusmn/0.01 with little dispersion around 1.55 /spl mu/m. Very low loss single-mode waveguides with metal electrodes showing very low polarization dependence of loss coefficient are fabricated using wet oxidized Al/sub x/Ga/sub 1-x/As 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 Al/sub x/Ga/sub 1-x/As are compared with conventional designs using only compound semiconductor heterostructures.