Fiber Lasers and Amplifiers: High‐Power Operation

Abstract

Since their invention in the beginning of the 1960s, fiber lasers have been improved from a helical shaped laser rod with an embedded waveguide structure to highly sophisticated laser systems that caused a revolution in telecommunications. In four decades of development, the wavelength range has been extended to the visible, ultraviolet, and mid‐infrared regime applying different rare earth–doped host glasses. Whereas diode laser pumped fiber lasers with emission in the visible spectral range became of great interest for applications in multimedia, measurement technique, medicine, and photofinishing, high‐power infrared, and high‐energy short‐pulse fiber lasers have been qualified for applications in thermal printing, marking, and material processing. However, nonlinear effects and the damage threshold of standard laser fibers hampered a straightforward scaling of the output power. Research is focused on these issues to develop scaling techniques for high‐power operation of infrared and visible upconversion fiber lasers in cw and pulsed modes. Nonlinear effects and power resistant fiber cores are factored into the fiber laser design. The fundamentals and the current state of the art of fiber lasers operating in the visible and infrared spectral ranges will be discussed in this work.