An APD/FET optical receiver operating at 8 Gbit/s

A high-sensitivity optical receiver has been designed for a bit rate of 8 Gbit/s and wavelengths of 1.3-1.55\mu 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 \bar{P} as high as -25.8 dBm was measured for 10-9bit-error rate.