Abstract

Two-micron lasers are of great interest for a range of applications, from spectroscopy to polymer machining and laser surgery, as well as being an important stepping stone for wavelength generation further into the mid infra-red band. Tm-doped silica fibre lasers are especially attractive as they are capable of operating at wavelengths from below 1700nm to more than 2100nm, and can be pumped by commercially available high power laser diodes operating around ~793nm. Moreover, by optimising the dopant concentration within the Tm fibre core a beneficial two-for-one cross-relaxation process can be exploited allowing efficiencies far-above the quantum limit for 793nm pumped Tm fibre lasers [1]. Indeed, efforts to optimise the core composition to enhance this process have been the subject of many studies, but as yet the best slope efficiencies reported for high power cladding-pumped Tm doped silica fibre lasers remain well below the theoretical maximum (~80%).

© 2015 IEEE