International audienceWe present an experimental investigation of a vertical-cavity surface-emitting laser (VCSEL) submitted to orthogonal optical injection, i.e., the injected light is linearly polarized and orthogonal to that emitted by the solitary VCSEL. Bifurcation boundaries of qualitatively different dynamics are mapped out in the frequency detuning-injection strength plane. We unveil rich and complex dynamics including injection locking, limit cycle, wave mixing, and period doubling route to chaos
International audienceBistability as well as dynamics associated to polarization switching in a vertical-cavity surface-emitting laser (VCSEL) submitted to orthogonal optical injection from an external master laser are investigated. Intensity-polarization switching bistability is studied by increasing and decreasing the intensity of the injected beam and for a fixed frequency detuning, i.e. the frequency offset between master and the free running VCSEL. Depending on the frequency detuning, bistable switching is experimentally found to occur with or without injection locking of the fundamental mode to the master laser frequency. For large positive detuning, injection locking of the first-order transverse mode with a strong depression of the fundamental mode has been observed. The case of frequency – polarization switching bistability, i.e. when the frequency detuning is first decreased and then increased for a fixed injected power, has also been theoretically analyzed. Qualitative comparison with previous experimental work is presented for the dependence of the width of the bistable switching region on the injection strength level. Finally we show an experimental result of complicated dynamics including period doubling route to chaos that accompany polarization switching and which motivates future theoretical investigations
Brussels (Belgium).The vertical-cavity surface-emitting laser (VCSEL) has attracted much attention due to its numerous advantages with respect to the conventional edge-emitting lasers. The VCSEL generally emits a linear polarization but its direction is not fixed a priori since polarization switching may occur as the operating conditions, i.e. the injection current or the temperature, are modified [1]. The optical injection from an external source of light may help to control or stabilize the VCSEL polarization and its study is interesting both from the point of view of dynamical instabilities and for applications in high density optical storage and optical signal processing [2].We report on an experimental and theoretical study of the polarization dynamics of a VCSEL submitted to optical injection. In our configuration, the linearly polarized injected light is orthogonal to the light emitted by the free running VCSEL [2]. The optical injection leads to a bistable polarization switching with or without injection locking, the switching power being strongly dependent on the frequency detuning (Fig. 1). For large positive detunings, we observe the locking of the first order transverse mode to the master laser and the suppression of the fundamental transverse mode. The polarization switching induced by optical injection may be furthermore accompanied by a mode hopping regime, i.e. a random hopping between the two linearly polarized modes. The statistical properties of the residence time are influenced by the optical injection strength and frequency detuning. On the other hand, the optical injection may stabilize an otherwise mode hopping VCSEL. Our experiment unveils a rich nonlinear polarization dynamics, which we map in detail in the plane of the injection parameters (injection strength, frequency detuning). Several different time-periodic dynamics are observed as a result of multiwave mixing or Hopf bifurcation. These timeperiodic instabilities may further bifurcate to a period doubling route to chaos, as shown in Fig. 2: an increase of the injected power leads first to a polarization switching with injection locking (b). The stationary state then undergoes a
International audienceWe investigate experimentally and theoretically nonlinear dynamics and polarization bistability in a vertical-cavity surface-emitting laser (VCSEL) submitted to an external optical injection with orthogonal polarization, i.e., the injected light from a master laser (ML) is linearly polarized and orthogonal to the polarization direction of the free-running VCSEL (slave laser, SL). Depending on the injection power level and the frequency detuning between ML and SL, our experimental results show that the injected VCSEL may undergo complex dynamics including subharmonic resonances and period-doubling route to chaos that are associated to polarization switching (PS). Using continuation method, we carry out a detailed bifurcation analysis and report on qualitatively different dynamics as we change the injection strength and/or the detuning. We show that PS may be strongly influenced by the presence of those dynamics. Our numerical results reveal period doubling dynamics that emerge from a Hopf bifurcation associated to an elliptical polarized injection locking state. Pure frequency-induced polarization bistability, i.e., when the detuning is changed for fixed injection power, is studied theoretically. Our results show that, depending on the level of the fixed injection strength, frequency induced PS may be achieved with or without hysteresis
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