Optical signal distribution to MSM photodetector arrays via integrated polyimide waveguides

The integration of metal-semiconductor-metal (MSM) photodetector arrays with polyimide ridge waveguides is demonstrated. MSM detectors were fabricated using transparent indium tin oxide (ITO) interdigitated electrodes on semi-insulating GaAs substrates. An optical buffer layer of SiO/sub 2/ was deposited and patterned, and then polyimide ridge waveguides were fabricated on top by spin coating and photolithography. The guides were multimode with widths from 10 to 50 /spl mu/m. Light at 830 nm was coupled efficiently from the waveguides through gaps in the SiO/sub 2/ buffer layer into the underlying detector structures. Absolute responsivities of the integrated MSM devices were around 0.5 A/W and the 3 dB bandwidths of 5-6 GHz were measured. Division of the input signal between sets of two and four detectors under a single waveguide has been achieved, highlighting the potential for the fabrication of integrated optoelectronic switches.