The output intensity of a hybrid bistable system with a delay in the feedback loop is known to undergo regular and irregular self-pulishg. With the help of high-resolutin power spectra, we have analyzed numerically the transition of this system into chaos for several different valus of the delay thime, and found evidence for the exzistence of an infinite sequence of period-doubling bifurcations. followed by a reverse sequence in which the periodic components of the spectrum are supperimposed to a continuous noisy structure. We jave stidoed tje effect pf extermal Gaussian random noise and verified, as expected, the occurrence of bifurcation gaps. In the vicinity of the self-pulising threshold, more than three independent frequency components coexist without evidence for the appearance of a strange attractor.

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.

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.

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.

This paper reports the phenomenon of frequency-unlocking in an electro-optical bistable system and proposes a method to control the frequency-unlocking state through controlling the chaotic output oscillation of the system. We successfully carry out a numerical simulation experiment, and then discuss the characteristics of the method and its physical nature. q1999 Elsevier Science B.V. All rights reserved.