OPTICAL LINKS FOR CRYOGENIC FOCAL-PLANE ARRAY READOUT

An optical link can provide an interface channel for a focal plane arr ay that is immune to electro-magnetic interference (EMI) and can lower the heat load on the dewar. Our approach involves the use of fiber op tics and an on-focal-plane optical modulator to provide an interface t o the focal plane array (FPA). The FPA drives the modulator with an el ectrical signal. We evaluated specially fabricated AlGaAs/GaAs multipl e-quantum-well (MQW) optical modulators, operating near 840 nm, for an alog modulation, and we have used the results to calculate the perform ance of an optical interface link using experimentally determined devi ce parameters. Link noise and dynamic range for an analog link were es timated from a separate experiment using pigtailed fiber components. T he performance of the MQW modulator system is compared to alternative strategies. Significant improvement in performance in comparison to co nventional electronic interfaces appears to be possible.