In-well pumping of a membrane external-cavity surface-emitting laser

We present a detailed characterization and comparative study of a membrane external-cavity surface-emitting laser (MECSEL) operating in the =1125-1190 nm wavelength range under in-well pumping (at 1070 nm) and barrier-pumping (at 808 nm). The slope efficiency of the laser is significantly improved from 21% with barrier-pumping to 39% when pumping only the quantum wells at 1070 nm at a heat-sink temperature of 10 C. To address the low pump absorbance with in-well pumping, we design and implement a low-aberration multi-pass pumping scheme. An optical output power of 28.5 W and slope efficiency of 28% is achieved with 8 circulating passes. This represents the highest output power demonstrated in any MECSEL, as well as the highest output power in-well pumped vertical external-cavity surface-emitting laser (VECSEL). It is noted that our reported output power is only limited by the available laser input power and no thermal roll-over is observed.