This research carries out coherence measurements of a 42.7 GHz quantum dash (QDash) semiconductor laser when passively, electrically, and optically mode-locked. Coherence of the spectral lines from the mode-locked laser is determined by examining the radio frequency beat-tone linewidth as the mode spacing is increased up to 1.1 THz. Electric-field measurements of the QDash laser are also presented, from which a comparison between experimental results and accepted theory for coherence in passively mode-locked lasers has been performed.
© 2012 Optical Society of America
Lasers and Laser Optics
Original Manuscript: September 13, 2012
Revised Manuscript: October 19, 2012
Manuscript Accepted: November 5, 2012
Published: November 29, 2012
Eamonn Martin, Regan Watts, Laurent Bramerie, Alexandre Shen, Harry Gariah, Fabrice Blache, Francois Lelarge, and Liam Barry, "Terahertz-bandwidth coherence measurements of a quantum dash laser in passive and active mode-locking operation," Opt. Lett. 37, 4967-4969 (2012)