Development of a high power, quasi-single-mode fiber laser for drilling holes on a thin metal plate at distance of 500 m from laser head

We present the development of a high-power quasi-single-mode fiber laser system with an output of approximately 1.5 kW continuous-wave and M 2 < 1.15, designed for long-range target engagement. An all-fiber structure with a pump laser diode (LD) of 915 nm and a Yb 3+ -doped fiber with a core diameter of 20 μm was used for the emission of a ∼1064 nm laser with the Optical-to-Optical (O-O) conversion efficiency of ∼ 70%. Collimation optics was developed to match the numerical aperture of the laser, producing a nearly collimated beam that can be effectively focused at long distances. The experimental results showed that the system successfully drilled holes on a 1 mm thick stainless-steel plate within 5 s at distances ranging from 20 m to 500 m. The results confirm the feasibility of using a high-power quasi-single-mode fiber laser for long-range material processing and combat applications.