Design of the 1650-1700nm U band doped fiber laser

Abstract

Increasing the power of thulium-doped fiber lasers is an important direction for the future development of fiber lasers. Thulium ions exhibit excellent optical properties in the U-band, making them valuable for research. This paper has established a modular design process for fiber lasers, investigating the energy level system of Thulium ions, electron transition processes, power propagation equations, pump power threshold, laser output power, and Bragg grating reflectance for specific wavelength photons. The reflectance of the front and rear cavity mirrors and Bragg grating was also redesigned. Finally, by establishing a physical model and employing numerical simulations, the relationship between laser onset power and pump light input power was determined: when the pump light input power reaches 10.1W, a population inversion occurs, and the fiber laser begins to generate laser output power. The laser output power linearly increases with the increase in pump light input power. When the pump light input power reaches 100W, the laser output power reaches its maximum value of 14.17W. This provides valuable data support for the laboratory preparation of 1650-1700nm thulium-doped fiber lasers.