Abstract

Distributed feedback laser diodes (DFB-LDs) are considered desirable single-longitudinal-mode light sources applicable to coherent transmission systems, because they are small in size, highly stable against mechanical vibration, and show no mode hopping over a wide current and temperature range. We have applied DFB-LDs to the optical heterodyne detection transmission experiment for the first time. As the DFB-LD emission spectral width is a few tens of megahertz, we selected the ASK heterodyne detection scheme which can tolerate an IF carrier having a relatively wide spectral width. As much as 10-dB receiver sensitivity improvement compared with direct detection has been obtained without degradation even after 30-km transmission with a 100-Mbit/sec NRZ signal using 1.3-μm wavelength DFB-LDs

© 1984 Optical Society of America