An integrated hybrid-chip-fibre platform for the generation of mid-infrared light

The laser is, without doubt one of the most important, discoveries that have been made in the last century and within a few decades, visible and near-infrared (IR) laser light has found a vast number of important applications in industry and research. The discovery of low-loss optical fibres was another revolutionary step that underpinned the rise of the global telecommunication industry. The mid-IR region of the electromagnetic spectrum spanning from about 2 – 20 μm, has recently been identified as a powerful tool for sensing and medical applications due to the strong and highly specific interaction of light at these wavelengths with molecules. However, while lasers based on silica-fibres have proven to be the most versatile and efficient light sources in the visible and near-IR, those glasses become virtually opaque at mid-IR wavelengths and new solutions are required. In this work, mid-infrared fibre lasers that are based on fluoride-glass optical fibres and on femtosecond laser-inscribed chalcogenide glass integrated chips are investigated. In detail, this project is aimed at studying the feasibility of fabricating a wavelength-selective 3-D integrated coupler in Gallium Lanthanum Sulphide (GLS) glass. The demonstration of the first fibre pigtailed 4-port device in the mid-infrared is a prerequisite for the future realisation of the first fully integrated mid- infrared ring laser. This, in turn, would further open the possibility to develop monolithic all-fibre mode-locked lasers that are based on non-linearly coupled waveguide arrays.