Simulation study of an adaptive phase alignment system for opticalheterodyne communications under misalignment conditions

摘要

A postphotodetection adaptive phase alignment system using annaperture array of photodetectors is presented to reduce the signal lossnin an optical (free-space) heterodyne receiver resulting from wavefrontnmisalignment (tilt) on a satellite platform. This paper compares twonkinds of rectangular aperture configurations-full aperture and arraynaperture configurations-via a software simulation study of the errornperformance after DPSK demodulation for different angles of arrivaln(tilt) of the received signal wavefront. For the array configuration, annadaptive phase alignment system is used that phase aligns the signalsnfrom the different photodetector array elements, and constructively addsnthem to yield a higher signal magnitude as compared to that of signal ofna single-element photodetector of the same total area. The optimumnaperture length for a given wavefront misalignment is derived, and isnverified via simulation