Nonlinear Dynamics in Semiconductor Lasers - Abstract
Reitzenstein, Stephan
Micro- and nanolasers offer a rich spectrum of exciting physics at the crossroads between nanophotonics and quantum optics. Due to their low mode volume, they operate in the regime of cavity quantum electrodynamics to establish high spontaneous emission coupling factors (beta-factors) and to approach the ultimate limit of thresholdless single emitter lasing. Up until now, studies of such lasers have been focussing almost exclusively on the properties of the lasers themselves without considering their interaction with other passive or active optical elements and devices. This is quite amazing since external control and coupling of lasers is well known to address many fascinating effects of non-linear dynamics, such as zero-lag synchronization of mutually coupled microlasers or the possibility of implementing neuromorphic reservoir computing in networks of coupled lasers. We explore non-linear dynamics at optical powers well below 1 µW by using electrically driven micropillar lasers. Such lasers feature beta-factors close to unity and lasing operation maintained by the gain contribution of only a few tens of quantum dots. These characteristics make them particularly interesting for the study of non-linear dynamics in the ultra-low power regime with strongly enhanced spontaneous emission noise and with less than about 100 photons in the laser mode. In this regime, we perform experiments on time delayed self-feedback, injection locking and mutual coupling of high-beta microlasers to approach the quantum regime in which a countable number of emitters and photons becomes important for the device operation. Our studies reveal intriguing phenomena such as partial injection locking, which are unknown for conventional lasers. Of particular interest is the mutual coupling and synchronization of microlasers which targets the question whether synchronization exists in quantum systems and how it relates with quantum mechanical entanglement.