Fibre Lasers

Abstract

Fibre lasers were first demonstrated in 1963 when a multimode fibre was transversely pumped by an incoherent light source [1J. There has been a recent revival of interest in fibre lasers because of the development of techniques for fabricating single-mode fibres doped with impurities but with very low losses characteristic of silica fibre used for optical communications. The fabrication technique can be applied to many dopants including most of the lanthanide series and some transition metal ions. The attractive features of fibre lasers include the low threshold, the freedom from thermal distortion problems, the availability of broad gain profiles so that tuning may be achieved and ultimately so that short pulse generation may be achieved in a mode-locked system. Thus in many ways fibre lasers present features available in dye lasers but with additional advantages such as the ability to Q-switch, long term stability of the laser medium, the compact configuration, the absence of cooling requirements and the ability to diode pump. Furthermore the confined mode volume provides low threshold and high gain enabling continuous-wave three-level laser operation.