A model for the analysis the dynamical behaviour of a twin stripe laser oscillator is developed. It consists of a laser with two active stripes with slightly different effective indices of refraction accounting for different active indices, and for the existence of two modes (symmetric and antisymmetric). The analysis is based on two laterally coupled one-dimensional transmission lines. Oscillating optical signals at the laser output are observed, if both stripes are independently biased with direct currents, without any modulation. The
main characteristics of these oscillations, as well as their dependence on several parameters of the devices, are shown. The main features of the oscillations are, that the frequency is above the relaxation oscillation frequency, and that the phase noise of the oscillations is much lower than in the beat signal of two solitary
lasers. Finally, the modulation depth of the signal is optimized, and the linewidth is evaluated.