Optical networking and signal-processing applications of 790 nm self-pulsating laser diodes

Abstract

A series of investigations into the networking and signal-processing applications of 790 nm self-pulsating lasers is described. These devices, which were developed for optical disc interrogation, offer the response speed and power output expected of laser diodes but with substantially reduced coherence. This combination of properties is achieved by an appropriate cavity design which results in self-sustained, high-extinction-ratio oscillation at frequencies extending beyond 2 GHz. The resulting low-coherence emission substantially reduces modal noise in multimode fibre networks. Additionally, optoelectronic signal processing functions such as microwave injection-locking and carrier extraction are possible. We present two sets of experimental results. First, single-channel-per-laser subcarrier networking with respective aggregate throughputs of 450 Mbit/s and 1 Gbit/s over three binary phase shift keyed (BPSK) and five (quaternary phase shift keyed) QPSK channels is reported. Secondly, experimental observation of 1 GHz injection-locking together with 750 MHz and 1.5 GHz carrier extraction from BPSK and QPSK subcarrier signals centred on 375 MHz is described. Future applications for this work may be found in the areas of computer networking and optoelectronic signal-processing.