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.
Ultrafast vortex pulses emitted at 1 μm band are highly sought after in many fields, here we propose an all-fiber laser for achieving that. The designed laser is switchable to emit ultrafast orbital angular momentum (OAM) and cylindrical vector beams. The beam purities are calculated to be higher than 94%. Moreover, the as-designed laser can achieve ultrafast pulse with a duration of 10.4 ps and maximum energy of 619.3 pJ. Generally, it is the shortest width and largest energy of OAM emission in ultrafast ytterbium-doped all-fiber laser so far.
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