Abstract

Taking a comprehensive consideration of related excited state absorption, upconversion emission, and cross relaxation processes, a theoretical model concerning a pulsed Yb-Tm fiber laser is established. The criterion for stable Q-switching is derived with both excited state absorption processes and mode field area mismatch taken into account. And, detailed population transitions of major energy levels are illustrated. Impacts of pump power, mode field area ratio and saturable absorber length on the output characteristics of the pulsed laser system are investigated and analyzed. Simulations show that the excited state absorption transition ³F₄→³F_2,3 is the predominant factor supporting the passive Q-switching of Yb-Tm fiber lasers. Besides the pump power, the mode field area ratio and the length of the saturable absorber are also important factors affecting the output characteristics of the pulsed laser system. Proper choice of these parameters not only brings significant improvements to the pulse performance, with regards to both the pulse energy and the pulse duration, but also expands the stable operation range of the laser system. And, in practice, an effective mode field area ratio bigger than 1.65 should be exploited for the stable Q-switching operation of a pulsed Yb-Tm fiber laser.

1030-nm passively Q-switched ytterbium-doped fiber laser using excited-state absorption of thulium fiber

Tzong-Yow Tsai and Zhi-Cheng Lee
Opt. Lett. 45(1) 17-20 (2020)

Effects of excited-state absorption on self-pulsing in Tm³⁺-doped fiber lasers

Yulong Tang and Jianqiu Xu
J. Opt. Soc. Am. B 27(2) 179-186 (2010)

Fiber laser with simultaneous multi-wavelength Er/Yb passively Q-switched and single-wavelength Tm gain-switched operations

J. Alaniz-Baylon, M. Durán-Sánchez, R. I. Álvarez-Tamayo, B. Posada-Ramírez, M. Bello-Jiménez, B. Ibarra-Escamilla, A. A. Castillo-Guzman, and E. A. Kuzin
Photon. Res. 7(6) 608-614 (2019)

Passive Q-switching by Tm³⁺co-doping of a Yb³⁺-fiber laser

P. Adel, M. Auerbach, C. Fallnich, S. Unger, H.-R. Müller, and J. Kirchhof
Opt. Express 11(21) 2730-2735 (2003)

Saturable absorber Q- and gain-switched all-Yb³⁺ all-fiber laser at 976 and 1064 nm

Tzong-Yow Tsai, Yen-Cheng Fang, Huai-Min Huang, Hong-Xi Tsao, and Shih-Ting Lin
Opt. Express 18(23) 23523-23528 (2010)