The University of Southampton

Silica Fibre Fabrication

Fabrication of silica based optical fibre has been the core of the ORC’s fibre research since the formation of the ORC. Silica optical fibre and devices made from these types of fibre form the majority of the components used in the optical telecommunications industry as well as many other uses in high power lasers, sensing, light transmission etc. 

At the ORC we have access to a multi-million pound cleanroom equipped with several systems for fabrication and research on most aspects of silica fibres. The work of the fibre fabrication group is interdisciplinary. Candidates to work in this group require a background in any one of materials science, physics, engineering and chemistry.

Group webpage 

All PhD Projects: 

  • Entry Requirements: A very good undergraduate degree (at least a UK 2:1 honours degree, or its international equivalent) in physics or a related discipline. 
  • Funding: Full tuition plus, for UK students, an enhanced stipend of £20,000 tax-free per annum for up to 3.5 years. Limited funding for international applicants may be available. Overseas students who have secured or are seeking external funding are also welcome to apply.
  • How to apply: Applications should be made online
  • Closing date: Applications are accepted throughout the year and several start dates throughout the year are possible. Applications for the typical Sept./Oct. 2023 start should be received no later than 31 August 2023.


PhD Projects:

Development of advanced rare-earth doped optical fibres for high-power lasers

Supervisory team: Professor Jayanta Sahu

We are looking for PhD applicants with a background in physics, material sciences, chemistry, and engineering to work on a PhD project that is aiming to develop a new class of optical fibres for the next generation of high-power lasers. This project will be carried out in close collaboration with an industrial partner, a leading manufacturer of specialty optical fibres. The successful candidate will be part of a world-leading research team working on fibre fabrication and fibre lasers and amplifiers at the Optoelectronics Research Centre (ORC). The student will also have the opportunity to spend a period of time with the industrial partner.

Fibre lasers that are increasingly becoming the light source of choice for a wide range of industrial and scientific applications, have spurred the development of new types of rare-earth (i.e., Yb, Er, Tm, and Ho) doped fibres, each with a unique set of properties to match with the specific applications. Since the fibre design and material properties of the fibre core have become critical to the performance of the fibre laser, a more powerful fibre fabrication process is required than the current industry standard process, which is MCVD (Modified Chemical Vapour Deposition) - solution doping technique.

In this PhD project, we will develop novel optical fibre materials and fabrication techniques for realisation of advanced rare-earth doped fibres with tailored dopant profiles and large core, as required for the next generation of high power fibre lasers and amplifiers. 

The student will have access to the world-class Zeple Institute cleanroom complex with a state-of-the-art fibre fabrication facilities. The project is also required a significant element of high power laser work. At the end of this PhD project, the student will have the opportunity to develop a wide range of skills, which include specialty optical fibre fabrication and characterization of rare-earth doped optical fibres, while acquiring knowledge on high power fibre devices.


Bismuth-doped fibre amplifiers for extended transmission bands in optical communications

Supervisory Team: Prof Jayanta Sahu, Dr Yu Wang

Global internet traffic has been growing exponentially over the past two decades with a predicted growth rate of around 40% year-on-year. This growth is driven primarily by bandwidth-hungry applications such as cloud computing, Telemedicine, 4K live streaming and is expected to continue in the era of the Internet of Things and 5G. However, the present optical fibre communication network’s capacity is solely based on the 11THz (C and L bands) gain bandwidth of erbium (Er) doped fibre amplifiers (EDFA) invented three decades ago. The scaling of the overall transmission capacity requires next-generation optical fibre amplifiers with ultra-broad gain bandwidths to further utilise the low-loss window offered by the solid- and hollow-core silica optical fibres. 

In this PhD project, we aim to develop efficient Bi-doped fibres and to demonstrate next-generation ultra-broad Bi-doped fibre amplifiers in the wavelength band covering from 1150-1500nm and 1600-1750nm. In the process of developing Bi-doped fibres, the student will also study spectroscopic properties such as absorption and emission cross-sections to understand the near-IR luminescence in these fibres. The focus will be on experimental work but can include simulations/modelling of new amplifiers based on the interests of the student. The performance of developed Bi-doped fibre amplifiers will be evaluated in collaboration with our academic partners. Our recent work on a record level of gain (40dB) and also first-ever wideband (115nm) Bi-doped fibre amplifiers have been well received in the scientific community and grasped significant attention from telecom industries.

We are seeking PhD applicants with a background in physics/chemistry/engineering/ materials science and a strong interest in optical fibre technology and/or laser/amplifier technology to work on this ambitious project. Throughout the PhD, the candidate will have access to state-of-the-art fibre fabrication facilities and laboratories at the ORC/Zepler Institute.

At the end of this PhD project, you will develop skills in specialty optical fibre fabrication and characterization of doped fibres, and will acquire knowledge on fibre lasers and amplifiers while having the opportunity to publish the work in high-impact journals and conferences.


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

Supervisory Team: Prof Jayanta Sahu, Dr Bill Brocklesby, Dr Arindam Halder

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. 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.

This PhD project aims to investigate a route to high-power visible sources through cladding pumping of RE-doped silica fibres using GaN-LDs. The student 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, the student will perform a detailed spectroscopic characterization of the fabricated fibres and will be involved in the development of visible fibres.

The project is suitable for someone with a background in physics/materials science/chemistry/engineering and with a strong interest in optical fibre technology and/or laser/amplifier technology. Throughout the PhD, the student will have access to state-of-the-art fibre fabrication facilities and laboratories at the ORC/Zepler Institute. You will develop knowledge and skills in fibre fabrication and characterisation of doped optical fibres, while learning or applying knowledge in high-power fibre lasers. 


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