Developments in high-power fibre lasers

In this tutorial, I will provide a brief history of the high power fibre laser and highlight the major developments that have led to this exponential improvement in the maximum output power over recent years. I will explain the fundamental concepts involved in the design of a high power fibre laser and I will also explain the important power scaling techniques that have been tested. I will emphasize some of the limitations on the performance of high power fibre lasers and I hope to illustrate how these limitations can be overcome. Finally, I will briefly discuss how high power fibre lasers can be used to pump other optical systems in order to extend the wavelength and pulse characteristics of the output. In this latter context, I will show the important achievements that have been made in relation to the construction of high power fibre lasers for the emission of mid-infrared output.