Timing jitter reduction of passively mode-locked semiconductor lasers by self- and external-injection: Numerical description and experiments

Abstract

In this paper the influence of different feedback (FB) and synchronization schemes on the timing phase noise (TPN) power spectral density (PSD) of a quantum-dot based passively mode-locked laser (MLL) is studied numerically and by experiments. The range of investigated schemes cover hybrid mode-locking, an opto-electrical feedback configuration, an all-optical feedback configuration and optical pulse train injection configuration by means of a master MLL. The mechanism responsible for TPN PSD reduction in the case of FB is identified for the first time for monolithic passively MLL and relies on the effective interaction of the timing of the intra-cavity pulse and the time-delayed FB pulse or FB modulation together with an statistical averaging of the independent timing deviations of both. This mechanism is quantified by means of simulation results obtained by introducing an universal and versatile simple time-domain model.

Experimental Study of the Timing Jitter of a Passively Mode-Locked External-Cavity Semiconductor Laser Subject to Repetition Rate Transitions and Optical Feedback

“…The aim is to identify the general optimum condition of OFB for the highest reduction of TJ. Hereby, the GC is kept at a fixed value of 154.5 mA and the RBV is kept at a fixed value of 1.75 V. Here, the TPN PSD is evaluated at an offset frequency of 120 kHz which represents an easily accessible measure of TJ [6]. The fine-delay is always optimized towards highest TPN PSD reduction.…”

“…1. In particular, this long-term timing jitter (TJ LT ) is also valid for the case of a PML SCL subject to OFB [6] and thus represents an ideal measure of TJ for the investigations presented here. To evaluate the TJ LT it is sufficient to estimate f rep and f .…”

“…It has been studied that this kind of OFB reduces variances in the pulse amplitude [4] and width [5] and the pulse timing jitter [6] compared to the non-resonant case.…”

Stabilization of class-B broad-area laser emission by external optical injection

“…Besides that, optical injection is also the well-established way to stabilize the parameters of lasers emission. In particular, it has been demonstrated experimentally and theoretically that locking the slave laser to the master one allows to reduce the noise-induced spectral broadening and stabilize the pulse waveform and leads to reduction of the timing jitter in mode-locked semiconductor lasers [36][37][38][39][40]. Strong optical injection was also found to overcome the self-focusing action owing to the gain-index coupling and suppress filamentation in broad-area semiconductor lasers [41].…”

Recent advances in ultrafast semiconductor disk lasers

“…In contrast to edge-emitting semiconductor lasers, SDLs have a very short interaction length of the optical pulse with the gain layers and the cavity losses are very low. The high-Q cavity intrinsically imposes a lower noise level 129,130 than semiconductor edge emitters [131][132][133] . The low-noise behavior and the possibility of stabilizing the repetition rate to an external reference source make ultrafast VECSELs and MIXSELs attractive laser sources for compact and cost-efficient frequency comb metrology applications.…”