Modulated spectral beam combining of diode laser array stack in an external cavity for the enhancement of beam quality

In the generation of side lobes, which is decided by mutual-locked mode (here, the definition of mutual-mode-locked is that the interference of space light between different emitters produces side lobes. where main lobe is decided by self-mode-locked, which is superposition after interference produced by the same emitters ) has a strong impact on beam quality for spectral beam combining of diode laser array stack in an external cavity. In this report, for the first time, the theoretical explanation of the interlocking mode is given, and the experimental results are in good agreement with the theoretical model. Secondly, a method of fully eliminating side lobes was presented. Finally, the implementation of spectral beam combining of diode laser bars is received, which contains six 800 nm Mini-Bars along the fast-axis direction in an external cavity. The output power of maximal 268 W with its combing efficiency of 100% and well-proportioned spectral distribution is achieved at 70 A of operation current, where the side lobes were fully eliminated. The results indicated that beam parameter product along the slow axis considered by one dimension is less than 8 mm × mrad. The beam quality is improved as a whole.