High-Power Single-Frequency Fiber Amplifiers

High-power single-frequency fiber amplifiers are increasingly dominant in technologies that require high optical power, stability, and coherence simultaneously. In this chapter, we first provide an overview of their key characteristics, applications, architectures, and components. We then review the nonlinear acousto- and thermo-optical instabilities that limit power scaling and summarize the primary mitigation techniques. Finally, we discuss multimode excitation with wavefront shaping and anti-Stokes fluorescence cooling as two emerging strategies to circumvent the limitations of current approaches.