Homodyne coherent optical receiver for intersatellite communication.

Abstract

For increasing the data rate and reducing the power consumption in satellite communication systems, free-space optical communication technology has been verified as an attractive alternative to traditional radiofrequency communication systems. In this study, a high-sensitivity homodyne coherent optical receiver was demonstrated. A sensitivity of -59.2 dBm was achieved with an unencoded bit-error rate below 10-3 at a bit rate of 1Gbps (9.4photons/bit does not include any overhead for forward error correction). To achieve homodyne detection, a modified decision-driven Costas optical phase-locked loop and a digital control algorithm were used to suppress the phase error and track the Doppler shift. Test experiments show that the receiver sensitivity penalty caused by the phase error is approximately 1dB and that the receiver can track a Doppler shift at the speed of 100MHz/s. Test experiments demonstrate that the receiver has a robust adaptive capacity to received-power fluctuation. The theoretical analysis and experimental results are presented in this paper.