Spectrum-locked high-power volume Bragg grating external-cavity diode laser

Spectrum-locked high-power diode lasers are extremely sought after in many fields. Here, we establish the volume Bragg grating external-cavity diode laser model and investigate the impact of facet reflectivity on the output spectrum. The simulation results emphasize that optimizing reflectivity can realize better spectrum-locking and side-mode suppression ratio. To prove the feasibility, we built a diode laser array with 20 single emitters. Three different facet reflectivity are prepared, 0.1%, 0.5%, and 0.8%. As a result, the output spectrums of the array are improved obviously with the decrease in reflectivity. In the case of 0.1%, the side-mode is well suppressed under injection current up to 16 A, and the calculated current-spectrum shift is around 0.07 nm A(-1). After beam combining and fiber coupling, an output power of 243.4 W and a brightness of about 11.2 MW cm(-2)-str is attained.