Performance in the presence of laser chirp of high speed optical communication systems employing semiconductor laser preamplifiers

The performance in the presence of laser chirp of optical receivers incorporating semiconductor laser preamplifiers is investigated quantitatively. The analyses make use of a lightwave system simulation package designed to accommodate transmitter, fiber, semiconductor laser amplifier, and receiver characteristics. Transmission at 4 Gb/s through a single-mode fiber (SMF) is simulated, taking into account the interaction between laser wavelength chirp and both fiber chromatic dispersion and optical-amplifier transmission characteristics. The results indicate that the mismatch penalty, arising from the transiently varying mismatch between the instantaneous laser wavelength and the peak gain-wavelength of the amplifier, can be reduced substantially by tuning the amplifier wavelength to 0.7-0.8 Å less than the static lasing mode of the laser