We study the dynamical response of a hybrid bistable system with a delay in the feedback loop when the input intensity undergoes a simple sinusoidal modulation. As a function of the driving frequency and modulation depth, we predict the appearance of frequency-locking phenomena and period-doubling bifurcations into chaos.

We study the response of a hybrid bistable system with a delay in the feedback loop when the input intensity is modulated sinusoidally. As predicted in an earlier publication [J.Y. Gao and L.M. Narducci, Optics Comm. 58 (1986) 360], our experiments confirm the appearance of resonance phenomena, frequency locking and period doubling bifurcations upon varying the parameters of the modulation and the operating conditions of the hybrid device.

We consider the small-signal response of a rate-equation laser to modulation of the laser cavity length. To avoid nonlinear resonances in modulators and power supplies, we demonstrate that one can hold the modulation frequency and amplitude fixed while varying the cavity detuning to change the resonant response of the laser to modulation, and thereby one can extract the relaxation oscillation frequency and the damping rate of those oscillations. This technique permits a careful study of the relaxation parameters of the laser that govern small oscillations and thereby permits discrimination among several different models recently proposed to describe CO2 laser dynamics. We demonstrate this method of analysis by applying it to such a laser experimentally with the result that the simple rate-equation model is shown to fail while the more complex vibro-rotational model satisfactorily describes the results.

A systematic study of the temporal evolution and of the power spectrum of the output intensity produced by a hybrid bistable system with a delay in the feedback loop has shown that self-pulsing and chaotic oscillations are the result of the nonlinear coupling among an infinite number of modes of the linearized system. The main qualitative differences observed both experimentally and in computer simulations between short-and long-delay-time regimes are caused by the emergence of progressively more unstable modes as the delay of the feedback is made larger. The fairly abrupt changes in the temporal patterns, which in earlier numerical studies havebeen interpreted as periodicity windows are, instead, the result of frequency locking among a large number of modes of the system. From this work we conclude that the short-and long-delay-time regimes do not differ fundamentally from one another, and can easily be described in terms of a common analysis.

e demonstrate a range of locking regimes of a self-pulsing bistable hybrid electro-optic device when the input light is modulated. In the larger locking windows we are able to clearly follow the phase shift between the frequency-locked response and the driving frequency. A related phase shift is observed in the "frustrated switching" of the bistable device (in the absence of selfpulsing) as the modulation frequency of the input light is lowered to the critical value.