We report on recent developments in fibre laser component technology for use in 2-micron laser systems. A
range of ‘building block’ components has been built to allow novel fibre laser architectures that exploit the
advantages of fibre lasers based on Thulium and Holmium active fibres. Fibre lasers operating around 2-microns
are becoming widely used in an increasing number of applications, which is driving the need for components
that can operate reliably at high powers and also integrate easily with other components. To that end, we have
designed and built a range of fused fibre, acousto-optic and magneto-optic devices that can be readily integrated
into a range of novel fibre laser systems.
Research has been carried out into improving fused fibre technology for components operating at 2um
wavelengths. Side-coupled feed through combiners have been developed with signal losses as low as 0.02dB
and kilowatt level end-coupled pump couplers. Alongside this a range of taps, splitters and WDMs have been
developed which allows for the implementation of a variety of laser architectures. Optical isolators based on
new Faraday materials have been developed, providing over 30dB isolation, low insertion loss and 30W power
handling in a fibre-in, fibre-out version. New cell designs and materials for Acousto-Optic devices have been
researched leading to the development of fibre-coupled Acousto-Optic Modulators (AOM) and allows for the
realisation of all fibre Thulium and Holmium Q-switched and pulsed fibre lasers. Novel Acousto-Optic Tunable
Filters (AOTF) designs have been realised to produce narrow resolution AOTFs and zero-shift AOTFs.