Ra. Salvatore et A. Yariv, DEMONSTRATION OF DOWN-CHIRPED AND CHIRP-FREE PULSES FROM HIGH-REPETITION-RATE PASSIVELY MODE-LOCKED LASERS, IEEE photonics technology letters, 7(10), 1995, pp. 1151-1153
Knowledge and control of the chirp parameters of semiconductor lasers
is a prerequisite to obtaining transform-limited pulses and/or to comp
ensate for group velocity dispersion in fiber, Here, we report measure
ments of the sign and magnitude of chirp in high-repetition-rate mode-
locked semiconductor lasers. The chirp of these monolithic lasers is m
easured in the frequency domain, using filtering and cross-correlation
techniques, For different injection currents, a range of different ch
irp values is measured, including strongly down-chirped pulses at high
er injection currents and transform-limited pulses to slightly up-chir
ped pulses at lower injection currents, The pulse chirp and the result
ing broadening are due to the algebraic addition of opposite-signed ch
irps due to saturation of the absorption section and the gain section,
These may cancel each other under some conditions, leading to a solit
on-like transform-limited pulse.