4x4 optoelectronic switch matrix integrating an MSM array with polyimide optical waveguides

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Abstract
Optical fibers offer the wide bandwidth, low losses and low interference required in broadband network applications. Currently, routing the signals to their destination is done by converting the incoming optical signals to an electrical form, carrying out the switching function using electronic circuitry then reconverting to light for the next transmission stage. Recently, we have reported a 3 by 3 optoelectronic switch which combines the functions of conversion and switching. This matrix monolithically integrates metal-semiconductor-metal (MSM) detectors with amplifiers. Very good isolation and crosstalk characterize this switch matrix, but the packaging requires the alignment of nine fibers, the square of the number of inputs, to the various detector crosspoints. In this presentation, we report the fabrication and evaluation of 4 by 4 optoelectronic switching matrices integrating MSM detectors with polyimide waveguides which perform the optical signal distribution on the wafer. These waveguides were fabricated on top of the semiconductor using a photolithographic process. The detector electrodes were formed using a transparent ITO film to maximize the responsivity. The incoming light is distributed using the 'tap' approach, which is more compact than the Y-branching configuration. Two 2 by 4 monolithic arrays were assembled on an alumina circuit using microwave hybrid circuit technology. The bandwidth of the assembled switch exceeds 1 GHz and with improved circuit design, should approach the 5 - 10 GHz bandwidth of the individual MSMs. A similar switch is based on a 4 by 4 monolithic array. The isolation is typically better than 35 dB. These characteristics are compared to the performance of the 3 by 3 OEIC switch and another 4 by 4 switch array assembled using four GaAs MESFET SP4T switches.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

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