Stability analysis of transverse modes in stripe - geometry injection lasers

We analyse the spatial stability of transverse modes in stripe-geometry injection lasers. A parameter is derived as a measure of the potential spatial instability of the modes. The analysis follows the interaction between the optical field and the charge-carrier density as described by the carrier-diffusion and wave equations. A perturbation is applied to an initial configuration of the system, a series solution for the perturbed system is obtained and an index is derived which determines the stability of the initial configuration. Numerical values for the index are obtained from self-consistent solutions of the device equations. It is shown how nonlinearities in the light/current characteristics of the device, together with near-field shifts, are related to values of the instability index in excess of unity.