Model and Characteristics of Self-Pulsing in ${\rm Tm}^{3+}$-Doped Silica Fiber Lasers

Abstract

In this paper, a theoretical model, taking into account the phonon-assisted excited-state absorption process ( <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> → <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ), has been constructed to explain the self-pulsing (SP) phenomenon in the Tm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -doped fiber lasers. Both numerical simulation and experimental investigation on the SP characteristics of ~2-μ.m Tm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -doped fiber lasers have been carried out. The numerical simulation shows agreement with the experimental results. Furthermore, the impacts of output coupling, pump intensity, and Tm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -ion doping concentration on the SP characteristics of the Tm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -doped fiber lasers have been studied explicitly, and optimization of the SP features has been discussed. In addition, the potential applications of SP in fiber lasers or solid-state lasers have also been proposed.