Abstract

We present a photonic integrated return to zero (RZ) transmitter for high-speed optical time-division multiplexed systems. The device monolithically combines a DBR laser and an electroabsorption modulator. Monolithic integrated laser-modulator devices have previously been reported for generating low-chirp nonreturn to zero (NRZ) signals for long-distance transmission (see, for example, Refs. 1 and 2). Here, an RZ signal is obtained by gain switching the laser section to provide a train of 50-ps pulses and encoding a pseudorandom signal by the integrated modulator. At a signal rate of 3 Gbit/s, a 2.8-dB improvement in receiver sensitivity is demonstrated compared to when the DBR laser is operated cw to generate an NRZ signal. The sensitivity improvement is, however, accompanied by a degradation in the optical spectrum.

© 1992 Optical Society of America