A high-sensitivity optical receiver has been designed for a bit rate of 8 Gbit/s and wavelengths of

m. The receiver uses a 60-GHz gain-bandwidth-product InGaAs/InGaAsP/InP avalanche photodiode followed by a high-impedance hybrid GaAs MESFET preamplifier. A bandwidth of 6.9 GHz was measured, with flat frequency response ±2 dB being obtained through the use of a 3-tap transversal equalizer. A sensitivity

as high as -25.8 dBm was measured for 10
-9bit-error rate.