OPTICAL LINKS FOR CRYOGENIC FOCAL-PLANE ARRAY READOUT

An optical link can provide an interface channel for a focal plane array that is immune to electro-magnetic interference (EMI) and can lower the heat load on the dewar. Our approach involves the use of fiber optics and an on-focal-plane optical modulator to provide an interface to the focal plane array (FPA). The FPA drives the modulator with an electrical signal. We evaluated specially fabricated AlGaAs/GaAs multiple-quantum-well (MQW) optical modulators, operating near 840 nm, for analog modulation, and we have used the results to calculate the performance of an optical interface link using experimentally determined device parameters. Link noise and dynamic range for an analog link were estimated from a separate experiment using pigtailed fiber components. The performance of the MQW modulator system is compared to alternative strategies. Significant improvement in performance in comparison to conventional electronic interfaces appears to be possible.