High-power quasi-CW diode-pumped 750-nm AlGaAs VECSEL emitting a peak power of 29.6†W and an average power of 8.5†W.

A peak output power of 29.6 W and an average output power of 8.5 W at a wavelength of 750 nm were demonstrated in quasi-CW multi-mode operation using an AlGaAs-based vertical external-cavity surface-emitting laser (VECSEL) diode-pumped at a wavelength of 675 nm. The comparatively low bandgap of the barrier material that was tuned to the pump-photon energy allowed a good compromise between low heat generation due to the quantum defect and strong absorptance of the pump radiation. The limitations for the average output power came mainly from insufficient heat flow from the intra-cavity heat spreader to the heat sink. These results show the potential for power scaling of diode-pumped VECSELs and the importance of effective heat removal.

2.5 W continuous wave output at 665 nm from a multipass and quantum-well-pumped AlGaInP vertical-external-cavity surface-emitting laser.

An output power of 2.5 W at a wavelength of 665 nm was obtained from a quantum-well (QW) and multipass-pumped AlGaInP-based vertical-external-cavity surface-emitting laser operated at a heat sink temperature of 10°C. Intracavity frequency doubling resulted in an output power of 820 mW at a wavelength of 333 nm. To the best of our knowledge, these are the highest continuous wave output powers from this type of laser both at the fundamental wavelength and in frequency-doubled operation. In fundamental wavelength operation, further power scaling by increasing the pump-spot size increased the output power to 3.3 W. However, at this power level, the laser was highly unstable. When the laser was operated at 50% pump duty cycle, a reproducible and stable peak output power of 3.6 W was obtained. These results demonstrate the potential of optical QW pumping combined with multipass pumping for the operation of AlGaInP-based semiconductor disk lasers.

Coherent coupling of vertical-cavity surface-emitting laser arrays and efficient beam combining by diffractive optical elements: concept and experimental verification.

A phase-locked diode-laser system based on master-slave coupling of two-dimensional vertical-cavity surface-emitting laser (VCSEL) arrays by injection locking is presented. Frequencies and phases are adjusted by laser-trimmed microresistors. Additional beam-transformation optics consisting of two diffractive optical elements (DOEs) and a Fourier lens concentrates most of the far-field power in a nearly diffraction-limited beam. Both the VCSEL array and the microlens array are monolithically integrated and mounted in a compact module. With an array of 21 slave lasers a system coherence of 95% (for several hours) and of nearly 90% (for several months) has been demonstrated without any active phase control. The scalability of the output power has been verified by locking of an array of 77 slave lasers with a system coherence of 78%. The optical system efficiency is 20-23%; with beam-transformation optics this efficiency could be improved to 44%.