A broad-area mode-coupling model for multiple-stripe semiconductor lasers

An analytical perturbation model is presented for calculating the eigenmodes of multistripe diode laser arrays. In contrast to the supermode theory, the array modes are developed into a linear combination of broad-area modes instead of individual waveguide modes. Two perturbations from which mode coupling originates are taken into account, namely the periodic gain and index grating formed by the current stripes and the effect of temperature variations across the junction. Results for the model are shown to be in excellent agreement with the experimental data, particularly concerning the details of the far-field structure of free-running diode arrays. The model provides a new physical interpretation of the coupling of modes due to temperature variations across the array width