Direct chip-scale optical frequency divider via regenerative harmonic injection locking.

A novel optical frequency division technique, called regenerative harmonic injection locking, is used to transfer the timing stability of an optical frequency comb with a repetition rate in the millimeter wave range (∼300GHz) to a chip-scale mode-locked laser with a ∼10GHz repetition rate. By doing so, the 300 GHz optical frequency comb is optically divided by a factor of 30× to 10 GHz. The stability of the mode-locked laser after regenerative harmonic injection locking is ∼10-12 at 1 s with a 1/τ trend. To facilitate optical frequency division, a coupled opto-electronic oscillator is implemented to assist the injection locking process. This technique is exceptionally power efficient, as it uses less than 100µW of optical power to achieve stable locking.

Towards On-Chip Self-Referenced Frequency-Comb Sources Based on Semiconductor Mode-Locked Lasers.

Miniaturization of frequency-comb sources could open a host of potential applications in spectroscopy, biomedical monitoring, astronomy, microwave signal generation, and distribution of precise time or frequency across networks. This review article places emphasis on an architecture with a semiconductor mode-locked laser at the heart of the system and subsequent supercontinuum generation and carrier-envelope offset detection and stabilization in nonlinear integrated optics.