1. Introduction to fiber laser sources

Before getting to the heart of the matter, it's important to give an overview of the performance of fiber lasers and the reasons for their success. The average power obtained in a diffraction-limited beam can reach several kilowatts in continuous operation. This impressive average power is due in part to the geometry of the optical fiber, which acts as a very good heat sink thanks to the high ratio between the surface area exchanged with the outside world and the total volume. This power reaches 50 kW for systems with less-than-perfect beam quality.

Fiber-optic sources can also be used to generate optical pulses. In both nanosecond and femtosecond pulse regimes, the average power generated is several hundred watts, and the energy limit per pulse is a few millijoules. These performances are generally achieved using ytterbium-doped fibers. Fiber lasers enable the...