'Fiber Lasers: Materials, Structures and Technologies'

摘要

Rare earth doped silica based fiber lasers and amplifiers have been shown to be suitable for a variety of applications in industry, science and medicine. They can yield very high power output both in the pulsed and cw regime with high efficiency, reliability and beam quality. Great progress was possible by new design concepts as non-symmetric double clads and large mode area core structures and by careful tailoring the material properties. Extreme power load and complicated fiber structures make high demands on the preparation technology. Special aspects of material and technology development will be discussed in the following. Basic requirement for a successful fabrication of defined fiber core compositions is the knowledge of the incorporation mechanism of the rare earths into the high silica matrix. Diffusion processes during the preparation steps determine refractive index distribution, geometry and numerical aperture. Strong concentration dependences of codopants and the interaction between co-dopants and active components must be taken into account. The optical properties of rare earths ions can be tailored by defined co-dopant relations according to the intended application. Some unusual basic loss contributions of certain rare earths have to be considered and controlled in order to get high laser performance. Loss effects by UV radiation play a role if UV cured coatings are used or if the fibers are provided with Bragg gratings as laser mirrors.