A theoretical and experimental investigation of an in-band pumped gain-switched thulium-doped fiber laser

In this paper, the theoretical rate equation model of in-band pumped gain-switched thulium-doped fiber (TDF) laser is investigated. The analytical formulations of pump energy threshold, peak power extraction efficiency, and pulse extraction efficiency are derived through analyzing the interaction process between pump pulse and laser pulse. They are useful for understanding, designing, and optimizing the in-band pumped TDF lasers in a 1.9 μm-2.1 μm wavelength region. The experiment of all fiber gain-switched TDF laser pumped by 1.558-μ pulse amplifier is conducted, and our experimental results show good agreement with theoretical analysis.