Wavelet analysis of burst synchronization in a coupled CO2 laser system

We investigate complex synchronization phenomena of a pair of coupled chaotic CO2 lasers. This system displays episodes of bursting of different predominant frequencies, i.e. it shows a multi-scale behaviour. In order to to resolve the different time scales in that system, we use a continuous wavelet transform. Furthermore by choosing a complex wavelet, the transform yields a direct estimate of the system's phase in dependence on time and frequency, which is the major advantage of wavelets in comparison with standard Fourier methods. We mainly find that, as the coupling strength of the laser system is increased, the mutual coherency increases differently for different frequencies. We analyze data from a numerically integrated model system as well as experimental data and find good coincidence.