Passively mode-locked surface-emitting semiconductor laser with >200 mW average power

Summary form only given. We recently demonstrated for the first time passive mode locking of a vertical-external-cavity surface-emitting semiconductor laser (VEC-SEL). The device was pumped with a diode laser and mode-locked with a semiconductor saturable absorber mirror (SESAM) This technology is expected to lead to very powerful and compact pulsed sources, with multi-GHz repetition rates. Compared to previous results, we have now obtained a much higher average output power of 213 mW and at the same time a significantly reduced pulse duration of 3.2 ps. This amounts to a 20-fold enhancement of the peak power, which is now 30 W. Semiconductor laser sources have previously reached such power levels only with amplifier systems or with synchronous pumping of VEC-SELs, using a powerful mode-locked pump source. In edge-emitting semiconductor lasers the average and peak power is limited by the small mode area, which cannot be easily increased. With optically pumped VEC-SELs these constraints are eliminated, and much higher powers are possible with accordingly increased mode areas. Diffraction-limited output, as required for mode locking, is obtained with an external cavity.