Advanced Fibre Technologies & Applications

There has been a massive investment in optical fibre telecommunications technology over the last 40 years. Optical fibres lie at the very heart of modern society, providing the information superhighways required within our global communication systems. 

Within the AFTA group we are developing the fibres, fibre devices, and system concepts required for next generation telecommunication systems and investigating new applications of the technology in areas beyond telecommunications including amongst others: high power pulsed fibre lasers, industrial materials processing, aerospace, biology, sensing and fundamental physics.

Group webpage

 

PhD Projects:

Novel, high power short pulse sources at wavelengths beyond two microns

Supervisors: Professor D. J. Richardson, Dr Jonathan Price

Driven by the ever-increasing range of applications at wavelengths above 1.9 microns, this project will develop novel ultrashort-pulse fiber laser technology to achieve world leading power levels. 

The target will be to create high power femtosecond lasers in the 2 micron wavelength region enabled by state-of-the-art fibres fabricated by groups working in the ORC cleanroom. Thulium/Holmium based mode-locked lasers, chirped pulse amplifier systems and high power supercontinuum generation will represent the core of the work. Power scaling will be a key aspect and while the theory established for silica fibers will underpin this, there is considerable novelty due to the changes in glass parameters at this wavelength. 

Using fibres made from novel glass types and microstructured fiber designs can be incorporated as needed. If it fits with the interests of the student then work on amplification using nonlinear Raman gain at wavelengths beyond 2.1 microns could also be pursued. 

This exciting new project will dovetail with the ORC’s related activities on 2-micron telecommunications systems (“Mode-Gap” and “Photonics Hyperhighway”) and high power fiber development (“LISA”).  

 

The development of next generation transmission
fibres and fibre amplifers

Supervisor: Professor D J Richardson - Multiple potential 
projects in conjunction with Drs F. Poletti and S.U. Alam

We are rapidly reaching fundamental limits in terms of how much information can be transmitted though the transmission fibres used in the networks of today (estimated at around 100 Terabit/s per fibre – 69 Terabit/s have now been demonstrated in the laboratory). This is limited by a number of factors including loss, cross-talk between channels due to nonlinear optical effects and the bandwidth of the amplifiers used. 

This project is concerned with looking at radical new transmission fibre and amplifier technologies that will allow scaling to the petabit/s and above regimes. The project will run alongside a major European project (MODEGAP) and a large EPSRC programme grant (HYPERHIGHWAY) exploring the problem of upgrading our basic internet infrastructure. In particular we will investigate the possibility of using multimode or multicore fibre to increase the data carrying capacity of an optical fibre cable and the difficulties to be overcome in amplifying the multiple data channels propagating within the same fibre.  

 

The fabrication and applications of holey/ 
microstructured fibres

Supervisor: Professor D J Richardson in conjunction 
with Dr M. Petrovich/Mr J. Hayes

Holey optical fibres, which comprise of a microscopic array of air holes in the centre of an otherwise solid fibre, present exciting new possibilities for a whole new generation of both active and passive optical fibre devices. This new form of fibre can possess optical properties that simply cannot be realised with conventional fibre types and looks set to play an important role in application areas as diverse as telecommunications, lasers, aerospace and fundamental physics. 

This project is concerned with the development of new fabrication techniques for this radically new form of fibre with a view to extending the range of possible fibre geometries (and hence the range of optical properties), improving the loss and precision with which these fibres can be made, and the development of new characterisation techniques. The project is also likely to require a significant element of device work in conjunction with the specialist individual groups who use these fibres within their immediate device/systems research programs. 

Specific ongoing research topics include the development of holey fibres for: nonlinear optical switching in high bit rate communication systems, high power laser delivery for laser machining and aerospace applications, high power (>100W) lasers, femtosecond pulse generation and compression and next generation communication networks. 

 

Optical processing and transmission in 
future optical networks 

Supervisor: Professor D J Richardson in 
conjunction with Dr P Petropoulos

The demand for transmission bandwidth in the world’s core networks increases by around 80% year-on-year. This demand is driven by new applications such as I-Player and U-Tube and the development of new High-Definition and Super High-Definition Video formats. Within the next 5 years the demand will start to exceed the capacity provided by current transmission technology, moreover the power levels required to route and switch all of this data are becoming unsustainable. 

Research is now desperately required to address the looming “bandwidth-crunch” and to develop techniques to make optical networks much more power efficient. Use of advanced modulation formats that exploit the phase as well as the amplitude of the optical is one means to improve the capacity as is the development of new amplifier technologies offering far greater gain bandwidths. Judicious use of optical processing is also likely to prove important as it can improve network flexibility and substantially improve the speed and energy efficiency - electronic circuits is simply too slow and power inefficient.

 Projects offered under this topic will build upon existing in-house programs. Specific topics of research include the optical regeneration of signals, ultrafast all optical header recognition and signal routing, new source and amplifier technologies and high bit-rate (>160Gbit/s) data transmission. The ORC has recently upgraded its telecommunication laboratories with state-of-the-art test and measurement equipment and has recently commissioned to a ~1000km testbed network that links us to our collaborators across the UK. This opens significant new research opportunities for us which we are only just beginning to exploit.

 

Next generation pulsed high power fibre lasers and 
amplifiers and their applications

Supervisor: Professor D. J. Richardson in conjunction with Dr Shaiful Alam

Fibre laser technology offers tremendous prospects for the development of compact, robust pulse sources capable of operating over an enormous range of pulse parameters spanning from the nanosecond down to the femtosecond regime. This project concerns the development of high power pulsed laser and amplifier systems based on diode-pumped, dual-clad rare-earth doped optical fibres. Semiconductor seed lasers with pulse durations ranging from the nanosecond to picosecond regimes will be used. We will also investigate application of the amplifier technology developed within this project to amplification of our femtosecond fibre lasers. 

This project aims to develop techniques to power scale the output from pulsed fibre laser systems to the >100W average power regime, and to investigate means to convert the output wavelength to anywhere from the UV out to the far IR using fibre and/or crystal nonlinearities. The project will involve the development of new fibre types, the development of new short pulse oscillator and amplifier configurations and concepts and the extension of nonlinear frequency techniques to ultrahigh average power levels. 

Applications of the technology will also be explored and elements of the work are likely to be performed in conjunction with industrial partners. In particular we will investigate use of the technology for imaging applications in biology where the ability to shape the spatial, temporal and frequency characteristics of the output light offer key benefits and industrial materials processing.  

 

The physics and applications of optical combs – from precision time, frequency and spatial measurements to terahertz signal synthesis

Supervisor: Professor D J Richardson in conjunction 
with Dr Radan Slavik

Using recent developments in laser and frequency conversion it has become possible to produce laser sources providing a comb of spectral lines with spectral frequencies accurate to parts in a thousand, million, million. Such combs have revolutionised the accuracy with which time, frequency and distance can be measured and are opening a host of new device and application opportunities. 

The ORC has recently acquired a state of the art comb laser system and is investigating uses across a range of application sectors including high frequency waveform synthesis, optical sensing and metrology. We are offering a PhD position in the area of comb technology which will involve working on the various ongoing projects that we are running. The project would suit applicants with an interest in ultrafast lasers/nonlinear optics and/or ultrahigh precision measurements.  

 

Coherent optical transmitter 

Supervisors: Dr Radan Slavik and Prof D J Richardson

Today’s communication systems use modulation of amplitude as well as phase to encode information enabling optimum use of the transmission bandwidth available. 

In optical fibre communications a modulator is used to modify the amplitude and phase of a laser to generate the complex signals to be transmitted. Besides the fact that these modulators are costly, the high-speed data needs to be multiplexed using electronics before being sent to the modulator, which becomes challenging as the required data speeds increase (e.g. 100 GBit/s and higher). 

Recently, we invented (patent pending) a new technique that uses multiple lasers to generate complex modulation format signals eliminating the requirement for an external modulator and complex high speed electronics. In our approach each laser is directly modulated with one simple stream of data (containing only ‘0 = off’ and ‘1=on’ levels) and their outputs are then coherently combined using a network of passive optical couplers to create the final desired complex phase and amplitude modulated signal. 

The project will involve development of the recently-invented optical transmitter in collaboration with our industrial partner Eblana Photonics - a leading manufacturer of semiconductor lasers and devices. 

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