Theoretical Study Of Chaotic Dynamics Induced By Optomechanical Nonlinearity

Cavity optomechanics,exploring radiation-pressure interactions between electromagnetic and mechanical systems,has shown important application value in the fields of quantum optics and nonlinear optics.Thanks to the optomechanical nonlinearity,the optomechanical systems provide an important platform for exploring novel quantum phenomena.Under the semiclassical approximation,optomechanical nonlinearity could induce many interesting phenomena,such as bistability,selfsustaining oscillation,and chaos phenomena.Interestingly,chaotic dynamics is an aperiodic long-term behavior in a deterministic system,and has sensitive dependence on the initial conditions.It is useful for implementing secret information processing and optical sensing,and hence the generation of chaos under optomechanics has recently attracted enormous attention.In this paper,we theoretically and systematically study the influence of optomechanical nonlinearity on chaotic dynamics,discover optomechanical intermittent chaos,propose a theoretical scheme to realize nonreciprocal chaos and reduce the power threshold of chaotic motion.The research content of this paper is as follows:1.We theoretically demonstrate intermittent chaos induced by radiationpressure nonlinearity in a general optomechanical system.In contrast to the general chaotic dynamics,this optomechanical intermittent chaos is characterized by a nearly periodic motion interrupted irregularly by the chaotic motion,and exists in a transitional parameter regime between the normal chaos and periodic windows.The route to intermittent chaos is identified by bifurcation diagrams,and the optimal parameter regime for achieving this intermittent chaos is presented by a phase diagram.This work broadens the realm of optomechanical nonlinear dynamics,and is feasible with currently available optomechanical technology.2.Since the unidirectional transmission characteristic of nonreciprocal optics and the study of chaos theory in extended cavity optomechanical systems have certain practical significance,we investigate theoretically nonreciprocal chaos in a spinning optomechanical resonator.We find that under the Sagnac effect induced by spinning a resonator,the chaotic motion can exhibit unidirectional behavior.More specifically,the chaotic motion takes place when the spinning resonator is driven in a chosen direction,whereas it cannot emerge when the driving laser is applied in the opposite direction.Moreover,due to the Sagnac effect,we show that nonreciprocal chaos can resist the backscattering losses.The underlying reason for these phenomena is that the Sagnac effect induces an opposite frequency shift between clockwise and counterclockwise optical modes.Our work opens up a new route to achieve nonreciprocal chaos with the current experimental technology and may provide theoretical guidance for the production of a directional chaos signal generator.3.Previous studies have predominantly concentrated on the nature of chaotic dynamics,the chaotic threshold has not been studied in depth so far.On the basis of previous research,we theoretically investigate the nonlinear dynamics of an optomechanical system,where the system consists of N identical mechanical oscillators individually coupled to a common cavity field.We find that the optomechanical nonlinearity can be enhanced N times through theoretical analysis and numerical simulation in such system.This leads to the power thresholds to observe the nonlinear behaviors(bistable,period-doubling,and chaotic dynamics)beingreduced to 1/N.Our work may provide a way to engineer optomechanical devices with a lower threshold,which has potential applications in implementing secret information processing and optical sensing.