Feedback induced instabilities in a quantum dot semiconductor laser

Abstract

Abstract:We analyse the properties of GaAs based quantum dot semiconductor lasers emitting near 1310 nm. The line-width enhancement factor is shown to depend strongly on device temperature, ranging from 1.5 at 20 o C to 5 at 50 o C. With optical feedback from a distant reflector, devices remained stable at 20 o C but displayed a range of instabilities at 50 o C, including irregular power drop-outs and periodic pulsations, before entering a chaotic regime. Such dynamical features are unique to quantum dot lasers -quantum well lasers are significantly more unstable under optical feedback making such a clear route to chaos difficult to observe.

Long-cavity quantum dot laser

“…In the experiment, 6 the laser output was stable at low feedback strength. As the feedback level was increased, the laser displayed irregular sequences of dropouts at the delay frequency until it finally became a stable periodic oscillation.…”

“…A strong optical feedback induces an instability range at high temperature. 6 These instabilities are very different from those commonly observed in quantum well lasers and cannot be explained in the frame of the conventional LK approach because experimental conditions include high pumping current, strong optical feedback, and a relatively long external cavity. The observations include periodic oscillations at the delay period, which evolve to chaos.…”

“…6. We propose a system of delaydifferential equations that predicts the appearance of the periodic dropouts, intermittency, and chaos in the QD laser output and is not limited by the assumption of low pumping current and weak optical feedback.…”

“…This noise-induced phenomenon was reported for conventional semiconductor lasers with optical feedback but is related to a different mechanism. 9 The experiments with QD lasers 6 and the modeling of Eqs. (1)- (4) demonstrate hysteresis with stable branches for the steady-state operation and for the periodic oscillations.…”

Periodic dark pulse emission induced by delayed feedback in a quantum well semiconductor laser

“…Carroll et al also reported a kind of stable dark pulse emission from a QD laser induced by the optical feedback from a distant reflector. 15 It was considered as a unique property of the QD semiconductor lasers. However, our experiment shows that with appropriate optical feedback, similar periodical dark pulses could also be obtained in a quantumwell semiconductor laser.…”