We briefly review the development of gain-switched rare-earth-doped fiber lasers and their applications in wavelength conversion to mid-IR,supercontinuum generation,and medicine in recent years.We illustrate the similarities between gain-switching and Q-switching techniques that will provide tools for the design and optimization of the gain-switched fiber lasers.From the nature of the gain-switched fiber lasers,benefits of this kind of lasers to 2-μm region and in-band-pumped(two-level system)laser systems are obvious.Advantages of in-band-pumped 2-μm lasers are discussed and analyzed with a simple numerical simulation in terms of Tm-doped fiber lasers.We also propose the key factors in the development of the gain-switched fiber lasers and predict the future tendency.
