High-power 100-fs SESAM-modelocked VESCEL (Conference Presentation)

Abstract

Ultrafast vertical external-cavity surface-emitting lasers (VECSELs) are versatile laser sources and feature high-power operation. To date the best modelocking results have been achieved with a semiconductor saturable absorber mirror (SESAM). Ultrafast optically pumped semiconductor disk lasers (SDLs) are compact, cost-efficient and provide excellent beam quality at gigahertz pulse repetition rates for applications such as for example multi-photon imaging, ultrafast communication and in particular self-referenced gigahertz frequency combs. The highest peak power obtained with an ultrafast VECSEL is 4.35 kW in 400-fs pulses and the shortest pulses until now are 107 fs at 3 mW average output power. Here we present a SESAM-modelocked VECSEL with pulses as short as 96 fs and 100 mW average output power. These are to the best of our knowledge the shortest pulses achieved by a fundamentally modelocked SDL and result in a very high peak power of 0.56 kW at a pulse repetition rate of 1.63 GHz. The short pulse duration was achieved by introducing a small amount of positive group delay dispersion with a single path through an external 2-mm thick ZnSe window plate that compensated the initially negatively chirped 107-fs output pulses. Currently the power is limited by the transition from fundamental modelocking to multi-pulse operation, which reduces the pulse peak power and introduces additional noise. Therefore, we present a study of the multi-pulse behavior of the high-power 100-fs SDL resulting from the complex modelocking mechanism. This study also provides an insight into special issues of pulse characterization that may suggest stable fundamental modelocking even if this is not the case.