We review advances in the timing stabilization of self mode-locked and passively mode-locked
frequency comb semiconductor lasers in the infrared spectral range. Prospects of pulse train timing and
amplitude stability control, intermode beat frequency or pulse repetition rate agility, timing
synchronization and high peak power optical pulse generation are discussed. A mechanism responsible
for the timing stability control and intermode beat frequency or repetition rate agility of monolithic self
and passively mode-locked semiconductor lasers by time-delayed optical self-injection and
synchronization is suggested and supported by a simple time-domain model. These research efforts
might become important for time-critical applications in future optical communications as well as for
spectroscopy, remote ranging and nonlinear bio-imaging.
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Dominik Auth, Institute of Applied Physics, Technische Universität Darmstadt, Darmstadt, Germany, and
Stefan Breuer, Institute of Applied Physics, Technische Universität Darmstadt, Darmstadt, Germany, and
John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, USA.