Fabrication of lead-gallium-bismuth (PGB) optical fibre for mid-infrared nonlinearity applications

Lead-gallium-bismuth (PGB) is a non-silica based glass that can be used in the fabrication of optical fibre with high nonlinearity, low transmission loss, high thermal stability, and a broad transparency window. With a nonlinearity two orders higher than that of the fluoride based fibres, it has attracted much attention worldwide for its potential application in the mid-infrared region, particularly for applications such as supercontinuum generation. The fabrication process of PGB optical fibre is immature, leading to relatively high transmission loss and limiting the output average power to a few hundreds of milliwatts. However due to its intrinsic advantages such as high nonlinearity, high thermal stability, and low transmission loss, there is huge potential to achieve a higher output power by further improving the fibre fabrication processes. In this paper, we document the design and demonstration of a PGB optical fibre fabrication aimed for the delivery and nonlinear applications in the mid-infrared region. Fabrication steps from glass melting, preform making and fibre drawing will be covered in detail. By optimizing each of the fabrication steps, we expect to be able to produce PGB optical fibres suitable for supercontinuum generation and other nonlinear processes in the mid-infrared region.