First investigation of the noise and modulation properties of the carrier-envelope offset in a modelocked semiconductor laser.

Optics letters

PubMedID: 27420486

Brochard P, Jornod N, Schilt S, Wittwer VJ, Hakobyan S, Waldburger D, Link SM, Alfieri CG, Golling M, Devenoges L, Morel J, Keller U, Südmeyer T. First investigation of the noise and modulation properties of the carrier-envelope offset in a modelocked semiconductor laser. Opt Lett. 2016;41(14):3165-8.
We present the first characterization of the noise properties and modulation response of the carrier-envelope offset (CEO) frequency in a semiconductor modelocked laser. The CEO beat of an optically-pumped vertical external-cavity surface-emitting laser (VECSEL) at 1030 nm was characterized without standard f-to-2f interferometry. Instead, we used an appropriate combination of signals obtained from the modelocked oscillator and an auxiliary continuous-wave laser to extract information about the CEO signal. The estimated linewidth of the free-running CEO beat is approximately 1. 5 MHz at 1-s observation time, and the feedback bandwidth to enable a tight CEO phase lock to be achieved in a future stabilization loop is in the order of 300 kHz. We also characterized the amplitude and phase of the pump current to CEO-frequency transfer function, which showed a 3-dB bandwidth of ~300??kHz for the CEO frequency modulation. This fulfills the estimated required bandwidth and indicates that the first self-referenced phase-stabilization of a modelocked semiconductor laser should be feasible in the near future.