We revisit the laser model with cavity loss modulation, from which evidence of chaos and generalized multistability was discovered in 1982 [1]. Multistability refers to the coexistence of two or more attractors in nonlinear dynamical systems. Despite its relative simplicity, the adopted model shows us how the multistability depends on the dissipation of the system. The model is then tested under the action of a secondary sinusoidal perturbation, which can remove bistability when a suitable relative phase is chosen [2]. Such a control strategy is universally known as “phase control” and it was first implemented in the same physical system but at different resonance frequencies [3].
The potential of this control technique has been validated on other paradigmatic chaotic systems such as the Duffing oscillator. In this particular case, it has been verified that the control is more sensitive when applied to the cubic term of the nonlinearity [4].
We recently demonstrated that phase control, which is classified as a nonfeedback method, can be converted to a closed loop control (feedback method) when a suitable adaptive filter is used on the chaotic signal to be processed [5].