Balanced dual-detector receiver for optical heterodyne communication at Gbit/s rates

A balanced dual-detector receiver which requires low local-oscillator power has been designed and fabricated for optical heterodyne detection at 1·5 ?m wavelength and Gbit/s rates. The receiver consists of two InGaAs PIN photodiodes connected with opposite polarities to a high-impedance GaAs FET amplifier. Frequency response, noise suppression and noise spectrum measurements are reported.