Amplitude noise suppression by intracavity phase modulation in a harmonically mode-locked laser

A fiber coupled semiconductor ring laser that employs both an amplitude and a phase modulator was built and actively harmonic mode-locked at a repetition rate of 10 GHz. The phase modulator was driven at the cavity fundamental frequency and its effects on the optical spectrum and the optical pulse train were analyzed. The intracavity phase modulation at the cavity fundamental frequency resulted in 40% lower optical pulse amplitude fluctuations and improved the stability of the optical spectrum. (C) 2018 Elsevier Ltd. All rights reserved.