Simultaneous wavelength beam combination and dark region compressing using a segmented coated step prism group for a fiber-coupled system

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Due to the beam dark regions along the fast axis direction of the semiconductor laser and the significant difference in beam quality along the fast axis and the slow axis directions, it is imperative to shape the beams before they are coupled into the target fiber. Additionally, wavelength beam combination is essential for an increasing number of high-power applications. Traditional beam-shaping methods usually employ two prism groups to compress the beam dark regions and perform wavelength beam combination, respectively. However, a higher number of prisms in the fiber-coupled system generally leads to increased optical loss and reduced system efficiency. In this paper, a segmented coated step prism group with two different wavelength beam combination films coated on the step prism is proposed and investigated systematically. Compared with traditional beam-shaping methods, this method uses a single prism group to compress the dark regions and perform wavelength beam combination simultaneously, reducing the number of prisms used and thus decreasing optical loss. The simulation results show that the fiber with a 200 µm core diameter and a 0.22 numerical aperture can accommodate four sets of semiconductor laser beams, achieving 2306.8 W output power with an optical conversion efficiency of up to 90.1%.