BROADER, FLATTER OPTICAL-SPECTRA OF PASSIVELY MODE-LOCKED SEMICONDUCTOR-LASERS FOR A WAVELENGTH-DIVISION MULTIPLEXING SOURCE

Using the time domain master equation for a complex electric-field pul se envelope, we find analytical results for the optical spectra of pas sively mode-locked semiconductor lasers. The analysis includes the eff ect of optical nonlinearity of semiconductor lasers, which is characte rized by a slow saturable amplifier and absorber. Group velocity dispe rsion, bandwidth limiting, and self-phase modulation were considered a s well. The FWHM of the spectrum profile was found to have a strong de pendence on group velocity dispersion and self-phase modulation. For l arge absolute values of the chirp parameter, the optical spectra resul t in equispaced continuous wave frequencies, a large fraction of which have equal power. (C) 1997 Optical Society of America.