SPATIOTEMPORAL DYNAMICS IN TWIN-STRIPE SEMICONDUCTOR-LASERS

The twin-stripe semiconductor laser, a system of two evanescently coupled nonlinear oscillators, shows complex spatio-temporal behaviour. Its dynamics is studied theoretically by numerical integration of a model system of coupled partial differential equations. The overlap of the evanescent optical fields and the diffusion of charge carriers determine the amount of nonlinear transverse coupling between the laser stripes. The concept of cumulants of the bit-number of a dynamical system composed of two sub-systems, and a characteristic spatio-temporal correlation function are introduced and applied to quantify the complexities in space and time as they are observed in the output signal of the twin-stripe laser. Depending on the distance between the adjacent oscillators, three dynamical regimes are identified: Sufficiently far apart, the two laser oscillators are uncoupled and the device shows a steady constant output signal. In the regime of medium coupling, randomly oscillating light pulses dominate the output signal. If both stripes are strongly coupled, both lasers oscillate with a (fixed) phase lag but chaotic intensities.