Numerical optimization of Nd-doped fiber oscillators for broadband and high-power 0.9 µm emission

High-power 0.9 µm lasers have garnered significant interest due to their potential applications in laser pumping and blue-green light generation. However, as one of the promising implementation methods, the Nd-doped fiber (NDF) lasers have only recently reached a hundred-watt-level output power at 0.9 µm. In this paper, by solving the rate equations that account for amplified spontaneous emission, we numerically investigate the effects of cavity parameters such as the reflectivity of fiber Bragg grating, the length, loss coefficient, and core-to-cladding ratio of NDF, and the pumping method on the 0.9 µm laser performance of NDF oscillators. The simulation results show that by systematically optimizing the cavity parameters, a maximum wavelength tuning range of 870.2 to 926.4 nm can be achieved with core pumping, while a maximum laser power of 143.2 W at 920 nm with a slope efficiency of 48.8% is predicted in a counter cladding-pumped oscillator. This work offers valuable insights into the cavity parameters that influence the performance of 0.9 µm NDF oscillators, potentially benefiting the practical implementation of broadband and higher-power output at this wavelength band.