Abstract
This paper presents the new concept of optical coherent receiver front end which can obtain optical
phase error signals in PSK (Phase Shift Keying) communication data as well as spatial tracking error
without any extra tracking sensor, leading to downsizing of inter-satellite laser communication terminals.
This new receiver front end consists an optical 90 deg hybrid mixer with free space optical components,
segmental photo detectors and RF electronics, to realize not only balanced detection of both in-phase
and quadrature components but also heterodyning detection of tip/ tilt error signals.
