Effects of injected light and optical feedback on directly modulated MQW lasers and OTDM multigigabit-per-second system performance

Injection-locked directly current modulated semiconductor laser transmitters are theoretically investigated with respect to transmission performance. By large signal simulation of laser, standard single-mode fiber propagation and direct detection optically pre-amplified PIN receiver, transmission distances of 80-120 km at 10 Gb/s and 40-60 km at 15 Gb/s have been evaluated with a bit-error-rate < 10-9 with reasonable power penalty. Exploiting fiber nonlinearities with higher power launched into the fiber is demonstrated to increase the transmission distance by about 40%. Additionally the dynamics of the residual chirp of the laser is shown to act favorably on transmission performance. Guidelines for operation conditions of injection-locked lasers depending on detuning between laser and slave laser and injected power are given. Gain switching including optical feedback and the gain- levering effect have been investigated with respect to pulse production for optical time domain multiplexing. A new method for short pulse generation is presented. It is based on single frequency CW light injection into an unmodulated single mode laser under nonstable locking- conditions. Repetition frequencies larger than 150 GHz can be achieved. By soliton generation in a dispersion shifted fiber pulse widths of less than 3 ps FWHM with a squared hyperbolic cosecans shape can be generated.