Phase noise insensitive orthogonal M-ary polarization state modulation (OMPSM) system in optical intersatellite link

Coherent optical communication system is expected to be a strong candidate for future ISL applications under the seriously power limited condition, because of its advantage of obtaining near-quantum-limited performance. This paper proposes an orthogonal M-ary polarization state modulation (OMPSM)/heterodyne detection system, which can perfectly remove the phase noise of a laser and attain a sensitivity improvement with the increase of the symbol level M in the presence of any phase noise. The fundamental principle of the proposed system is shown, and the receiver performance is investigated and compared to an orthogonal M-ary FSK system, theoretically. The results show that in the presence of large phase noise, OMPSM system can improve the sensitivity by more than 2.2 dB with less transmission bandwidth than OMFSK.