High-power high beam quality vertical-cavity surface-emitting lasers

High-power vertical-cavity surface-emitting lasers (VCSEL) can be used as the laser source of laser pumping, laser ranging, and LIDAR, etc. The material structure of VCSEL was rarely optimized directly for high power operation. The deterioration of beam quality of VCSEL caused by large emitting window for high power operation is becoming a key problem for the application of high power VCSEL. Two novel techniques were proposed to improve the performance of VCSEL. The reflectivity of n-DBR was slightly decreased to 99.3% instead of 99.7% as commonly used in conventional VCSEL. A record power of 102 W was realized at a current of 110A for a 500 μm-aperture VCSEL. Output powers of 103 W and 115 W were respectively demonstrated for a 5×5 2D array with the single emitter of 100 μm-aperture and a 8×8 2D array with the single emitter of 140 μm-aperture. For the deterioration of beam quality, microlens were directly integrated onto the emitting window by wet etching the GaAs subatrate. The divergent angle of a 6×6 2D array with the single emitter of 90 μm-aperture was suppressed to 6.6°, indicating a strong improvement compared with the divergent angle of 14.8° for an array without microlens. The results above shows that the performance of high power VCSEL is greatly improved by the optimization of n-DBR reflectivity and the integration of microlens.