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Postgraduate research project

High-power visible fibre lasers pumped by the down-conversion process

Competition funded
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Type of degree
Doctor of Philosophy
Entry requirements
2:1 honours degree
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Faculty graduate school
Faculty of Engineering and Physical Sciences
Closing date

About the project

You will investigate a route to high-power visible sources through cladding pumping of RE-doped silica fibres using GaN-LDs. You will be involved in the fabrication of RE (such as Pr3+, Dy3+ and Tb3+) - doped fibres in modified silica glass hosts offering low phonon energy while maintaining the other characteristics of silica fibres. Additionally, you will perform a detailed spectroscopic characterisation of the fabricated fibres and will be involved in the development of visible fibres. You will have access to the the state-of-the-art fibre fabrication facilities and laboratories at the Optoelectronics Research Centre (ORC) in the Zepler Institute.

The progress in GaN-laser diodes (GaN-LD) covering the wavelength range between 390nm to 460nm is promising as 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 glassed (such as ZBLAN) due to their lower phonon energy than the oxides. However, the fluoride glass fibres are known for their poor chemical durability, weak mechanical properties, higher background loss than silica fibres, and making them difficult to splice with most fibre components which are developed on silica fibres for an all-fibre laser system are the bottlenecks of these fibre lasers to further improve their performance.

Visible lasers are indispensable for applications such as display, underwater communication, microscopy and bio-photonics, optical storage, and materials processing. Currently, the mainstream of visible lasers development has relied on frequency conversion techniques. However, often such systems are complex and require incorporation of bulk elements into the cavity, and thus not suitable for making monolithic devices. On the other hand, most of the rare earth (RE) ions exhibit absorption lines in the blue spectral region and fluorescence in the visible region.

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