Chirp reduction for arbitrary pulses by amplified chirped-pulse self-phase modulation in dispersion-shifted fiber

摘要

Negatively chirped pulses, with different chirp value or temporal profile, can be easily generated by direct modulation of semiconductor lasers. In this paper, we describe a method of chirp reduction for such pulses by using chirped-pulse self-phase modulation (SPM) in dispersion-shifted fiber (DSF). By using an optical amplifier and adjusting the peak pulse power, positive chirp induced from the intensity-dependent SPM in DSF can compensate an arbitrary negative chirp in the pulse without changing the pulsewidth. We present for the first time the basic theory of chirped-pulse SPM. Chirp reduction of a 2.6-GHz train of gain-switched pulses was demonstrated experimentally, in agreement with the theory.