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. On completion of the PhD in this area the candidate will have gained skills in all these areas. Currently there are three PhD project proposed in this area:

1. Novel photosensitive materials for telecoms applications

Photosensitive fibre is used to produce fibre Bragg gratings which are often used as very high quality filters and dispersion compensators in optical telecom systems. These photosensitive fibres are made by adjusting the composition of the core of the optical fibre so that when exposed to UV light, the refractive index of the core can be modified. By exposing the core to a periodic pattern of UV light a Bragg grating can be produced in the core of the fibre. One of the limiting factors is the small magnitude of the refractive index change that can be achieved with traditional fibre. This project will investigate new fibre compositions and post fabrication techniques to enhance the photosensitivity of optical fibre.

2. New silica based materials for short (S-band) and long (L and L+ band) wavelength optical amplifiers

The recent revolution in optical telecommunications was principally enabled by the invention, here at the ORC, of the erbium doped fibre amplifier. This operates in a band around 1.5mm and thus most telecoms systems are limited to this wavelength band. Development of amplifiers that operate in adjacent bands (S and L, L+) will increase the number of wavelength channels available in a fibre, thus increasing the capacity of each fibre link. This project involves investigation of new materials suitable for providing gain at these wavelengths and fabrication / characterisation of fibre using these materials.

3. Reducing nonlinear effects such as stimulated Brillouin scattering, in optical fibre suitable for kilowatt fibre lasers

Currently there is a substantial interest in ultra high power fibre lasers. These lasers find applications in many areas including materials processing, medicine and defense. Fibre lasers are particularly attractive for these applications since they are compact, robust and deliver a high quality beam. One of the limiting factors when one attempts to scale the output power of fibre lasers to kW levels are nonlinear effects caused by the high intensities. This project will investigate new fabrication techniques required to fabricate fibre with novel geometries and tapered dopant concentrations along the length of the fibre, since these approaches can be used to minimise nonlinear effects.

Click here for a full list of PhD projects available at the ORC