We investigate the influence of the external cavity geometry on a vertical-external-cavity surface-emitting laser (VECSEL). In particular, we consider a V-shaped device geometry with the gain chip in between the out-coupling facet and saturable absorber mirror, such that mode-locked pulses travel through the gain chip twice per roundtrip. We analyze the dynamic changes in the laser output in dependence of the gain chip position within the external cavity using a numeric modeling approach based on the optical Bloch equations. We show that the cavity geometry can be engineered to favor certain dynamic regimes of laser operation, e.g., tuning the pulse repetition rate by higher harmonic mode-locking. In between the stable operation conditions, regions of complex dynamics and chaos are found.
|