Abstract

Optical time-division multiplexing (OTDM) is potentially a useful technique for increasing the bit rate of lightwave systems beyond the bandwidth capabilities of drive electronics. We report here a novel optical multiplexing and demultiplexing scheme using mode-locked extended cavity injection lasers and Ti:LiNbO₃ waveguide switch/modulators. An OTDM experiment is described in which two separate lasers are mode-locked and externally modulated at 2 GHz, and then optically multiplexed to a bit rate of 4 Gb/s. The 4Gb/s multiplexed signal is transmitted over 8 km of fiber, demultiplexed with a Ti:LiNbO₃ optical directional coupler switch, and received at low error rate. The experiments reported here extend our previous work on external modulation [1], OTDM using gain-switched lasers [2], and our work on mode-locking of extended-cavity injection lasers [3]. The mode-locked lasers provide an excellent means of generating short pulses at high repetition rates, using only narrow-band electronics. In addition, they offer the potential of good spectral purity - a key requirement for low distortion, high bit-rate transmission over long fiber lengths.

© 1987 Optical Society of America