10-Gb/s laser communication demonstration based on digital coherent technique

Digital coherent systems will play an important role for increasing throughput and for enhancing receiver sensitivity in optical inter-satellite communication. In this paper, we propose a low-complexity digital coherent system suitable for implementation on a space-grade field programmable gate array (FPGA). An experiment of 10-Gb/s dual-polarization quadrature phase-shift keying (DP-QPSK) using the proposed digital coherent system is demonstrated over 1.1-m free space path. The experimental results verify that the proposed system is capable of multi-level modulation and compensating Doppler shift.