High-data rate differential phase shift keying receiver for satellite-to-ground optical communication link

Abstract

The high data-rate satellite-to-ground coherent optical communication link is limited because the phase integrity of a beam is impaired when passing through the atmospheric turbulence. Based on the interference of two successive data bits in an unequal arm-length Mach-Zehnder delay interferometer, the differential phase shift keying receiver is suited for high data-rate satellite-to-ground coherent optical communication links due to its immunity of the wave front impairment when passing through the atmospheric turbulence. In the time-delay self-homodyne interferometric detection used in 2×4 90 degree optical hybrid, the optical path difference corresponds to the duration of one bit. The optical path difference is stabilized to below one thousandth of the wavelength by moving a finely motorized platform with the close-loop control using the phase feedback from the outputs of the 90 degree hybrid. The 2.5 Gbps optical communication link has already been verified between two buildings over a distance of 2.4km in the worst-case atmospheric conditions. The design and experimental results are given in this paper.