Experimental results are presented on the effect of coupling on synchronization of two coupled nonidentical Chua's oscillators. Two oscillators are coupled in unidirectional drive response mode. The driver is always kept in chaotic ͑single scroll, double scroll͒ state while the response oscillator is kept in various dynamical states as point attractor, single scroll periodic, chaotic and double scroll. The strength of coupling plays a crucial role on synchronization between the coupled oscillators. With decreasing coupling strength, two routes of transitions, one route is through lag and intermittent lag synchronization and another one is through intermittency have been observed in single scroll cases. But the situations are slightly different when the driver is double scroll chaotic. Lag synchronization and intermittent lag synchronization regimes are present in double scroll situation, but an intermediate intermittency regime between ILS and PS has also been observed.

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We report experimental observations of Shil'nikov-type homoclinic chaos and mixed-mode oscillations in asymmetry-induced Chua's oscillator. The asymmetry plays a crucial role in the related homoclinic bifurcation. The asymmetry is introduced in the Chua circuit by forcing a dc voltage. Then by tuning a control parameter, we observed transition from large amplitude limit cycle to homoclinic chaos via a sequence of mixed-mode oscillations interspersed by chaotic states. We provide experimental evidences that the asymmetry effect can also be induced in the oscillatory Chua circuit when it is coupled with another one in a rest state. The coupling strength then controls the strength of asymmetry and thereby reproduces all the features of Shil'nikov chaos.

Abstract. We report our experimental observations of the Shil'nikov-type homoclinic chaos in asymmetry-induced Chua's oscillator. The asymmetry plays a crucial role in the related homoclinic bifurcations. The asymmetry is introduced in the circuit by forcing a DC voltage. For a selected asymmetry, when a system parameter is controlled, we observed transition from large amplitude limit cycle to homoclinic chaos via a sequence of periodic mixed-mode oscillations interspersed by chaotic states. Moreover, we observed two intermediate bursting regimes. Experimental evidences of homoclinic chaos are verified with PSPICE simulations.

An experimental method for generating homoclinic oscillations using two nonidentical Chua's oscillators coupled in unidirectional mode is described here. A homoclinic oscillation is obtained at the response oscillator in the weaker coupling limit of phase synchronization. Different phase locking phenomena of homoclinic oscillations with external periodic pulse have been observed when the frequency of the pulse is close to the natural frequency of the homoclinic oscillation or its subharmonics.