Integrated optical silicon photodiode array

Abstract

Applications of integrated optical devices to optical communications or signal processing often involve light beam deflection or spatial Fourier transformation performed by optical waveguide lenses. In each of these processes information carried by the light beam can be converted to an electrical signal through use of a detector array. By integrating a detector array into an optical waveguide structure, optical scattering which would occur in coupling light out of the waveguide and into a detector array is eliminated so that the primary limitation on information capacity is the detector array resolution. We consider herein such an integrated optical waveguide detector array which uses silicon as the substrate. The use of silicon allows fabrication of CCD array scanning structures or other array addressing circuitry, signal enhancement circuitry, and signal processing circuitry on the same substrate as the optical waveguide. A silicon substrate is also advantageous for optical waveguide formation in that the thermallygrown Si0 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> layer which supports the thin-film optical waveguide has a low refractive index and a very smooth surface for waveguide deposition. Also, Si is well-suited for the formation of three-dimensional channel waveguides by preferential etching.