We analyze a simple model of dispersive optical bistability in a ring cavity filled with a Kerr medium in the presence of two and three (carrier and one sideband pair) different frequencies. The steady-state characteristics are shown and the condition for selective switching is studied. We show the phenomenon of the so-called competition for resonance between different frequencies. The characteristic phenomenon of locking of the output intensities is presented. The model of two frequencies may also be used to describe bistability in the presence of two different polarizations. For three frequencies our discussion is based on the rigorous propagation equations, which admit a real Hamiltonian description and are completely integrable. We also discuss a general numerical approach, based on a relaxation method, for finding steady-state solutions and checking their stability. The relaxation dynamics is physically related to a finite response time of the medium. The effect of this finite response time on the stability of the steady states and on the dynamics is also discussed.
We analyze a simple model of dispersive optical bistability in a ring cavity filled with a Kerr medium in the presence of two and three (carrier and one sideband pair) different frequencies. The steady-state characteristics are shown and the condition for selective switching is studied. We show the phenomenon of the so-called competition for resonance between different frequencies. The characteristic phenomenon of locking of the output intensities is presented. The model of two frequencies may also be used to describe bistability in the presence of two different polarizations. For three frequencies our discussion is based on the rigorous propagation equations, which admit a real Hamiltonian description and are completely integrable. We also discuss a general numerical approach, based on a relaxation method, for finding steady-state solutions and checking their stability. The relaxation dynamics is physically related to a finite response time of the medium. The effect of this finite response time on the stability of the steady states and on the dynamics is also discussed.
Using a simple model of a ring cavity comprising a cubically nonlinear medium, we analyze dispersive optical bistability in the presence of more than one spectral component. We show the phenomenon of so-called competition for resonance. In addition to presenting cavity characteristics for the cases of two and three different frequencies, we also discuss the general method for finding steady-state solutions and checking their stability. A simple and efficient algorithm, based on a relaxation method, is devised to find steady-state solutions satisfying appropriate boundary conditions. The relaxation dynamics is physically related to a finite response time of the medium.
The instabilities of a nonlinear optical medium with induced absorption in a ring cavity are theoretically analyzed. Stable, bistable, and unstable stationary solutions are found for various values of incident intensity and detuning. The dynamic treatment yields, in the unstable regime, oscillations of the transmitted intensity in various modes for constant incident intensity. If the medium relaxation time is short compared with the round-trip time, oscillatory solutions are obtained, which show strong locking of the oscillation frequency to multiples of the inverse round-trip time. If the round-trip time is comparable with the medium relaxation time, numerical integrations yield periodic solutions with substructures because of the mismatch of the two characteristic times.
We study the propagation of electromagnetic radiation through a ring-cavity device containing a dispersive nonlinear medium. Under conditions appropriate for introducing the slowly varying envelope approximation and for adiabatically eliminating the atomic variables, we calculate analytical expressions between the steady-state-output intensity and the input-field amplitude for two models of the nonlinear susceptibility, the two-level atomic medium and the Kerr medium. The stability of these curves is determined, with special attention given to changes in the thresholds by varying the return-trip phase shift, the linear absorption, and the reflection coefficients of the mirrors. We investigate the positive-branch instabilities resulting in a pulsing output intensity and calculate the bifurcation rate for the period-doubling hierarchy and the fractal dimension of our two-dimensional maps for the Kerr medium. The convergence of the bifurcation rate to a constant is slow, and we find, as in the publications of Snapp et al. [ Opt. Commun.40, 68 ( 1981)] and Carmichael et al. [ Phys. Rev. A26, 3408 ( 1982)], that this constant is consistent with that found for the class of one-dimensional maps with a quadratic maximum. This universal constant is observed over a large range of fractal dimensions for the chaotic attractor. Discussions of pulse-output bistability, intermittency, and anomalous switching are given.
Two input beams at the same frequency excite the counter-propagating modes of a bidirectional ring cavity. These modes are coupled in the presence of a homogeneously broadened nonlinear medium and the optical device acts as two bistable switches whose characteristics can be mutually controlled. After a proper account of interference between the forward and backward waves, new features of optical bistability in a bidirectional ring cavity are discussed. It is found that when the intensity of one of the incident beams is held fixed in a critical range, the device switches on but never switches off as the intensity of the other beam is first increased and then decreased to zero.
Absorptive, dispersive, and diffractive effects are studied in a nonlinear ring-cavity configuration containing an intrinsically bistable medium modeled generically by a nonlinear oscillator. The output intensity is shown to exhibit steady-state and periodic characteristics for constant input intensity, but no chaotic solutions are found. We find that the plane-wave analysis is inconsistent with the inclusion of diffraction effects and that periodic output characteristics are affected even for Fresnel numbers of order 1000. Our results are contrasted with previously reported experimental and theoretical work.
In Chapter 9 we discussed the case of a nonlinear cavity containing an active medium. In this framework, the outstanding phenomenon which arises is laser emission, and we calculated the stationary solutions for the ring laser. In this chapter, instead, we turn our attention to the passive nonlinear cavity and in this framework the outstanding phenomenon is optical bistability , i.e. the existence of two distinct stable stationary states that coexist for the same fixed values of the parameters in play. This phenomenon can arise also in the case of an active system contained in a cavity, as we have already noted in Section 9.1 and as we will discuss further in connection with the laser with injected signal, but it became popular from the studies of nonlinear passive optical cavities in the 1970s and 1980s. In contrast to the laser case, in the passive configuration we use an input coherent field, which is injected into the cavity. We discussed this case in Chapter 8 and derived a general equation for the transmission of the cavity (Eq. (8.23)), which we used for an empty cavity and for a linear cavity in Sections 8.4 and 8.5, respectively. In this chapter we will discuss the full nonlinear configuration. It is customary to identify two extreme cases of optical bistability called absorptive optical bistability and dispersive or refractive optical bistability . In both cases an essential ingredient to obtain the bistable behavior is the feedback action exerted by the mirrors of the cavity. In the purely absorptive configuration, in which there is exact resonance among the frequencies of the input field, of the atoms and of the cavity, the other essential ingredient is the saturable nonlinearity of the absorption. In the dispersive case, instead, the main feature is the nonlinearity of the refractive index. These two cases will be illustrated in Sections 11.1 and 11.2, respectively, both “exactly” and in the low-transmission limit.