Recent Advances In InGaAsP/InP Phototransistors

The sensitivities of three different detector/pre-amplifier configurations suitable as 1.3 pm optical fiber receivers -- a heterojunction bipolar phototransistor, a p-i-n photo-diode with a FET preamplifier, and an avalanche photodiode with a FET preamplifier -- are calculated and compared using recently published performance data. Use of a state-of-the-art low capacitance, high transconductance FET preamplifier promises to increase the sensitivity of a pin-FET receiver to the point that it is only 6-7 db less than that of a low noise, low leakage APD detector with the same FET preamplifier. Heterojunction phototran: sistors, however, have the simplest structure of any of the three receivers, are monolithic, and require the least amount of control circuitry, while having sensitivities comparable to those of the advanced pin-FET receivers.