About the project
This PhD project aims to investigate a route to high-power visible sources through cladding pumping of RE-doped silica fibres using GaN-LDs.
Visible lasers are indispensable for applications such as display, underwater communication, microscopy, bio-photonics, optical storage, and materials processing. Often, high laser power is required. So far, the mainstream of high-power visible laser development has relied on frequency conversion techniques.
However, often such systems are complex and require incorporation of bulk elements into the cavity, and thus are not suitable for robust, monolithic, devices.
On the other hand, most rare earth (RE) ions exhibit absorption lines in the blue spectral region and fluorescence in the visible region.
The progress in GaN-laser diodes (GaN-LD) covering wavelengths between 390 and 460 nm makes them promising pump sources for RE-doped solid-state lasers with direct emissions in the visible. To date, visible lasers utilising RE-doped fibres have been reported in fluoride glasses (such as ZBLAN) due to lower phonon energy than in oxide glasses, notably silica. However, fluoride glass fibres are known for their poor chemical durability, weak mechanical properties, higher background loss than silica fibres. Critically, they are also difficult to splice with silica fibre components. This makes it near-impossible to develop an all-fibre laser system and is a critical bottleneck to improved performance and commercial breakthrough.
The student will be involved in the design and fabrication of fibres doped with RE (such as Pr3+, Dy3+ and Tb3+) in modified silica glass hosts offering low phonon energy while maintaining the desirable characteristics of silica fibres.
Additionally, the student will perform a detailed spectroscopic characterization of the fabricated fibres and can take part in the design and evaluation of high power visible fibre lasers.
Throughout the PhD, the candidate will have access to state-of-the-art fibre fabrication facilities and laboratories at the Optoelectronics Research Centre (ORC).
At the end of the PhD project, the student will have developed knowledge and skills in:
- fibre fabrication
- characterisation of doped optical fibres
- high-power fibre lasers.
