INTEGRATED WAVEGUIDE—DETECTOR COUPLER FOR INTEGRATED OPTICS

Abstract

The leaky waveguide losses of an integrated waveguide—detector coupler (IWDC) structure in the Corning 7059 glass/SiO2/silicon system at A=0.6328 pm has been theoretically modelled and measured as a function of waveguide modal properties, polarization and particularly the SiO2 cladding layer thickness. Numerous couplers with SiO2 thicknesses from 0.15 pm to 0.8 pm were measured with coupling values of 400 dB/cm to 1500 dB/cm for TE and to 5800 dB/cm for TM; in good agreement with the four—layer leaky waveguide theory. We propose and demonstrate the first use of IWDCs as spatially compact optoelectronic crosspoints for switching applications by fabricating and testing a 2x2 switch with silicon photoconductive detectors in the IWDC. The passive power splitting in the integrated switch is close to the ideal fifty percent for a 2x2 matrix but the detectors are not optimum, with evidence of non-ohmic contacts which degrade the crosspoint isolation to best values of 35 dB and an impulse time response of typically 120 ns. For a photogenerated carrier diffusion limited crosstalk from 20 MHz to 340 MHz of —20 dB, crosspoint densities of >160 _2 000 cm are possible.