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 /mi 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 //m to 0.8 /mi 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.