Recent Advances in 3.5 <i>μ</i>m Erbium-Doped Mid-Infrared Fiber Lasers

The performance of mid-infrared Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -doped fiber lasers has dramatically improved in the last few years. In this paper, we present an overview of the progress in 3.5 μm fiber lasers based on the dual-wavelength pumping approach. The cross section of the excited state absorption transition used by the 1973 nm second pump is found experimentally. A numerical simulation of the expected Q-switched behavior of this fiber laser is presented. This shows that increasing the power of the 977 nm pump is important to achieve high-peak power pulses.