Injection Locking of Quantum-Dot Microlasers Operating in the Few-Photon Regime

Abstract

We experimentally and theoretically investigate injection locking of quantum dot (QD) microlasers in the regime of cavity quantum electrodynamics (CQED). We observe frequency locking and phase-locking where cavity enhanced spontaneous emission enables simultaneous stable oscillation at the master frequency and at the solitary frequency of the slave microlaser. Measurements of the second-order autocorrelation function prove this simultaneous presence of both master and slave-like emission, where the former has coherent character with g (2) (0) = 1 while the latter one has thermal character with g (2) (0) = 2. Semi-classical rate-equations explain this peculiar behavior by cavity enhanced spontaneous emission and a low number of photons in the laser mode.

Tailoring the mode-switching dynamics in quantum-dot micropillar lasers via time-delayed optical feedback

“…Analog to previous studies, no pronounced change in threshold current as well as no hysteresis of output intensity between the increase and decrease of the excitation current can be observed. These effects are masked by the high spontaneous emission noise which smooths out the gain clamping at laser threshold [13].…”

“…Particularly, lasing has been demonstrated in the single-QD regime [7] paving the way towards the limiting case of thresholdless lasing [8][9][10][11][12]. From the standpoint of nonlinear laser dynamics, high-β QD micropillar lasers show particular dynamical regimes not present in standard large-scale semiconductor lasers like partial injection locking [13]. Moreover, intrinsically nonlinear switching dynamics result from the gain-competition between the two…”

Mutual coupling and synchronization of optically coupled quantum-dot micropillar lasers at ultra-low light levels

“…In contrast, the above-threshold weak mode linewidth increases, which indicates a non-complete transition to laser action for this mode. Previous injectionlocking experiments in QD-micropillar lasers showed that a locking range of around 1 GHz [40] can be expected. In order to be able to resolve possible locking effects between the two microlasers, linewidths smaller than the expected locking range and hence output powers of at least 30 nW are required (see Fig.…”

Dynamics of many-body quantum synchronisation

“…Synchronisation has been studied in a wide range of classical systems [2], as well as in systems such as lasers where semiclassical descriptions prove accurate [3,4]. Over the last few years experiments have begun to investigate synchronisation in smaller-scale oscillator systems, including micron-sized mechanical oscillators [5][6][7][8] and lasers operating in the few-photon regime [9]. Recently, theorists have also started to explore synchronisation in oscillators where a fully quantum mechanical description becomes essential [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29].…”