Topological Insight into the Non-Arrhenius Mode Hopping of Semiconductor Ring Lasers

Abstract

We investigate both theoretically and experimentally the stochastic switching between two counter-propagating lasing modes of a semiconductor ring laser. Experimentally, the residence time distribution cannot be described by a simple one parameter Arrhenius exponential law and reveals the presence of two different mode-hop scenarios with distinct time scales. In order to elucidate the origin of these two time scales, we propose a topological approach based on a two-dimensional dynamical system. 42.55.Px,42.60.Mi Fluctuations in active optical systems such as lasers is one of today's technological challenges as well as a fundamental problem of modern physics as they are the result of the quantum nature of the interaction between light and matter [1]. Fluctuations are e.g. responsible for longitudinal mode switching in semiconductor lasers [2], polarization mode-hopping in Vertical Cavity Surface Emitting Lasers (VCSELs) [3][4][5], and they play a fundamental role in stochastic and coherence resonances of optical systems [6][7][8].Semiconductor ring lasers (SRLs) are a particular class of lasers whose operation is strongly affected by stochastic fluctuations. The circular geometry of the active cavity allows a SRL to operate in two possible directions, namely clockwise mode (CW ) and counter-clockwise mode (CCW ). From the application point of view, SRLs are ideal candidates for all-optical information-storage. [9][10][11]. From a theoretical point of view, SRLs represent the optical prototype of nonlinear Z 2 -symmetric systems [12], which appear in many fields of physics.Fluctuations induce spontaneous abrupt changes in the SRL's directional operation from CW to CCW and vice versa, and therefore represent a major limitation to their successful applications for instance as optical memories. An in-depth understanding of the mode-hopping in SRLs would shed light on the stochastic properties of the large class of Z 2 -symmetric systems. In spite of its importance, the problem of spontaneous directional switches in SRLs remains unaddressed, partly due to the high dimensionality of the models that have been proposed for SRLs [9,13].In this paper, we address the problem of such fluctuations both theoretically and experimentally. We experimentally investigate the properties of the residence time distribution (RTD) that quantifies the mode hopping. Our theoretical analysis is based on an asymptotic reduction of a full rate-equation model to a Z 2 -symmetric planar system [14].We consider here an InP-based multiquantum-well SRL with a racetrack geometry and a free-spectralrange of 53.6 GHz. The device operates in a singletransverse, single-longitudinal mode regime at wavelength λ = 1.56µm. However, it will be clear from the rest of the discussion that our analysis is general and applies to any kind of ring geometry. A waveguide has been integrated on the same chip in order to couple power out from the ring. This bus waveguide can be independently biased in order to reduce absorption losses. The waveguide crosses the fa...

Generation linewidth of mode-hopping spin torque oscillators

“…The general form of such an extension was found to agree with the equations describing multi-mode ring lasers [35,36] and thus support mode-hopping. However, the model equations remained qualitative and their relation to experimental observables was not explored.…”

Optical injection in semiconductor ring lasers

“…A value of θ = −π/2 corresponds to unidirectional CW operation, while a value of θ = π/2 corresponds to unidirectional CCW operation. The validity of this two-dimensional phase space has been confirmed by experiments on a solitary SRL [18,19].…”

“…However, optical injection can also give rise to very intricate dynamics, which may obstruct the desired dynamical behavior. The particular Z 2 -symmetry of the SRL and its resulting phase space structure has already led to results such as alternative switching mechanisms [15,17], multistable regimes [18] and non-Arrhenius mode-hopping [19]. The different dynamical regimes resulting from forcing the SRL through optical injection will be disclosed in this paper.…”

Square-wave oscillations in a semiconductor ring laser subject to counter-directional delayed mutual feedback

“…5960, 140.3560, 190.3100 Semiconductor ring lasers (SRLs) exhibit unique dynamics due to interactions of the longitudinal modes in both counterclockwise (CCW) and clockwise (CW) directions [1][2][3][4][5]. Depending on the bias current, a free-running SRL has different operating regimes including bidirectional, unidirectional, and unstable lasing [1].…”