Loss Enhanced Phase Locking in Coupled Oscillators

Abstract

Phase locking, which is achieved by transferring some energy from one oscillator to the others, strongly depends on the coupling strength between the oscillators. Typically, the coupling strength must be above a certain threshold in order to achieve phase locking. Here we show how this threshold can be significantly reduced when phase-dependent losses are introduced into the oscillators. Specifically, the coupling strength can be reduced by at least an order of magnitude, thereby substantially decreasing the needed transfer of energy between oscillators. The resulting enhancement of phase locking does not only influence the laser research area, but also affects many other areas that involve coupled ensembles.

Theoretical study on phase locking of the array of fiber lasers coupled by bi-dimensional mutual injection

“…The loss mechanism plays an important role in phase locking of the array, which may make two sorts of arrays perform differently. 35 Phase locking is a key issue to understand the array of mutually-injected fiber lasers, and many studies were focused on it. Phase locking of the array consisting of a small quantity of fiber lasers was experimentally investigated in Refs.…”

Synchronized Cluster Formation in Coupled Laser Networks

“…We identified a specific substructure that imposes its synchronization state on the entire network and show that for any coupling configuration the network forms at most two synchronized clusters. Our results indicate that the synchronization state of the network is a nonlocal phenomenon and cannot be deduced by decomposing the network into smaller substructures, each with its individual synchronization state.It is well known that lasers can synchronize to lock their optical phases when the coupling delay time between them is relatively short (compared to the coherence time) [1][2][3][4]. Moreover, optical phase synchronization between two lasers can also occur even when the coupling delay time greatly exceeds the coherence time of the lasers themselves [5][6][7].…”

Phase locking of two coupled lasers with many longitudinal modes

“…c 2018 Optical Society of America Phase locking of two coupled lasers operating with only one longitudinal mode was investigated over the years [1][2][3][4]. It was shown theoretically and experimentally that a simple relation exist between the coupling strength that is needed for phase locking and the frequency detuning between the lasers [4][5][6]. While a sharp transition from no phase locking to full phase locking when the coupling strength exceeds a critical value is predicted, the experimental results revealed a gradual transition, which could be explained by introducing noise to each laser [4,6].…”

“…It was shown theoretically and experimentally that a simple relation exist between the coupling strength that is needed for phase locking and the frequency detuning between the lasers [4][5][6]. While a sharp transition from no phase locking to full phase locking when the coupling strength exceeds a critical value is predicted, the experimental results revealed a gradual transition, which could be explained by introducing noise to each laser [4,6]. For lasers with many longitudinal modes it was shown that for strong coupling strength only common longitudinal modes survive, leading to full phase locking [7][8][9][10].…”

“…The combined output power was detected by fast photo detector which was connected to a RF spectrum analyzer, to measure the beating frequencies and determine the longitudinal mode spectrum at the output [5]. We also measured the phase locking between the two fiber lasers by detecting the interference of small part of the light from each laser with a CCD camera, and determining the fringe visibility [6]. The longitudinal mode spectrum was measured at first when θ = 0 (κ = 0) and then sequentially repeated such measurement, each after rotating the QWP by 1…”