Synchronization of chaos in microchip lasers by using incoherent feedback

Abstract

We propose a chaos-synchronization scheme using incoherent feedback to the pumping power in two microchip lasers. The population inversion of the slave laser is controlled for synchronization by using the detected signals of the peak heights of chaotic pulse intensities in the two lasers. Matching of the optical frequencies between the two lasers (i.e., injection locking) is not required for synchronization using this method. We numerically demonstrate the incoherent feedback method and investigate synchronization regions against parameter mismatching between the two lasers. Synchronization is maintained within a mismatching of 1% for all laser parameters, which implies that the difficulty in reproducing the synchronized laser pulses is very useful for applications of secure optical communications.

Transient behaviour analysis of injection-locked lasers

“…In this analysis the following assumptions are necessary. (1) The field is linearly polarized. (2) The cavity modes of the ring lasers are plane waves.…”

“…In the absence of the injection signal, none of the terms on the left-hand side of equation (1) in the Fourier space has an overlap, and as mentioned in the previous paragraph, equation (1) can be rewritten for each of the terms separately. In other words, since the Fourier transform is a unitary transformation on the L 2 ([0, L]) space and the inner product is invariant under the unitary transformations, the Fourier transform of orthogonal functions is orthogonal:…”

“…Injection of coherent radiation into a laser oscillator is known to affect seriously the nonlinear dynamics of a free-running oscillator, causing a large variety of effects which are of considerable interest from experimental as well as theoretical points of view [1][2][3][4][5][6], in particular in applications such as lidar ranging, selective photochemistry, laser induced plasma physics, optical logic gates and optical pumping. Injection locking represents an effective technique for stabilizing powerful laser oscillators which would otherwise have a highly unstable emission output.…”

Synchronization of chaos in microchip lasers and its communication applications

“…In this subsection, we describe a chaos-synchronization method using 'incoherent' (independent of the optical phase or frequency) feedback [10] to achieve a synchronization that is independent of the injection locking effect and that satisfies narrow parameter regions for synchronization against parameter mismatch. In this method, two signals of the laser intensity for the master and slave lasers are detected simultaneously, and the amount of feedback-control signal from the subtraction of the two detected signals is calculated.…”

Effects of Lattice Structure in the Dynamics of Coupled Elements

“…Recently, networks of coupled elements have been successfully applied to model particular dynamical features of physical systems such as lasers [1], electric circuits [2], connected oscillators [3], and many others [4,5]. In general, underlying these networks there is some characteristic connection topology [6], which is defined essentially by [7] the average path length , i.e.…”