A 1.2Gb/s optical DPSK heterodyne detection transmission system using Monolithic External Cavity-DFB LDs

An optical PSK heterodyne detection system has the advantage of higher receiver sensitivity, compared with ASK and FSK systems. But since it requires higher coherencies for optical light sources, He-Ne lasers or external cavity LDs have been utilized in optical PSK heterodyne detection experiments.1)2)3) However, when stability and practicability are considered, it seems desirable to use solitary LDs in the system.