VECSEL and MECSEL: high power, wavelength versatility and ultra-short pulses (Conference Presentation)

Semiconductor disk lasers, also called vertical external-cavity surface-emitting lasers (VECSELs) have advantageous properties such as high output power, wavelength flexibility due to bandgap engineering and near-diffraction limited beam quality. The possibility to insert intra-cavity elements – filters, frequency doubling crystals or semiconductor saturable absorber mirrors (SESAMs) – enables wavelength tuning, second harmonic generation or mode locking with ultra-short pulses. A major challenge for these laser sources is the removal of heat which is introduced by optical pumping. The thermal management can be improved by placing only the active region directly between two heat spreaders. This membrane external-cavity surface-emitting laser (MECSEL) allows emission in an even larger wavelength range, since the growth is not restricted by a distributed Bragg reflector. We present the fabrication, processing and characterization of VECSELs and MECSELs using different material systems for laser emission at various wavelengths in the visible and in the infrared spectral range. Our semiconductor structures are grown by metal-organic vapor-phase epitaxy and contain quantum wells or quantum dots in the active regions. We discuss our latest results including the membrane laser concept with investigations of strain effects on the photoluminescence and the laser emission, different pumping schemes and ultra-short pulse generation.