• Boyland, A. J.
• Payne, D. N.
• Yoo, S.
• Webb, A. S.
• Kalita, M. P.
• Nilsson, Johan
• Jeong, Y.
• Sahu, Jayanta Kumar
• Maran, J.-N.
• Clarkson, W. A.

Abstract

The development of low loss, rare-earth doped, silica fibers in the mid-1980s revolutionized optical communications through the discovery of erbium-doped fiber amplifiers (EDFAs). Following the successful implementation of EDFAs in communications, high-power cladding pumped fiber lasers and amplifiers have, over the last decade, become a major field of operation of rare-earth doped fibers that now significantly opens up the use of fiber lasers in non-telecommunications markets. Fiber lasers benefit from a waveguide geometry that facilitates tight confinement of pump and signal beams over arbitrary length, providing characteristics such as low threshold, an output that can be easily tailored to produce single-spatial mode operation, a feasible three-level system, a broad gain bandwidth, and a high overall gain compared to bulk lasers. In recent years, the output power of fiber laser sources has been significantly increased to the point where the fiber based technology is now competing with conventional bulk solid-state lasers in applications such as micro-machining, welding and other material processing. In particular, ytterbium-doped fiber lasers have been power-scaled to several kilowatts at ~1.1 µm, with a nearly diffraction-limited output beam. In the power scaling process, nonlinear scattering such as stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) are viewed as the main challenges to overcome. Novel fiber devices, including those at other wavelengths and with different spectral properties have seen rapid progress. This presentation will review the progress in active fibers suitable for power scaling, highlighting the advances in fiber design and fabrication that will enable the control of nonlinearities in high power fiber lasers, as well as make feasible of a practical high power three-level system.

Topics

• impedance spectroscopy
• Ytterbium
• Erbium