Mode structure of a vertical-cavity surface-emitting laser subject to optical feedback

We present an analysis of the external cavity mode (ECM) structure of a vertical-cavity surface-emitting laser subject to optical feedback. We consider a model in which two transverse optical modes are excited. Furthermore, we allow weak coupling of the modes via the feedback term. (In addition to the coupling through the inversion.) We use numerical continuation techniques to find and follow solutions of the governing partial, delay differential equations. This approach allows us to show how the ECM structure depends on the key parameters of feedback strength, feedback phase and the amount of coupling via the feedback term