Summary

This area of research started in 2003 and has quickly established high quality research in secure quantum key distribution, photon sources, quantum gates and quantum measurement. Highlights in quantum photonics include the demonstration of a photonic crystal fibre-based pair-photon source, distance records in free space key-exchange experiments (2002 and 2007), the first experimental demonstration of an entangling quantum gate and quantum optical phase measurement with greater precision than classical techniques.

Looking further to the future we expect to see the principle features of quantum mechanics, those of wave-particle duality and entanglement, being exploited in computing and communications. Already we have developed secure key exchange schemes based on single photon communications. Such schemes could revolutionise how we secure our communications and financial transactions on an increasingly insecure internet. Bristol is now a world leader in this new field of Quantum Photonics with key successes in developing photonic crystal fibre light sources, quantum secured optical communications and novel quantum gate technologies.

Staff

• Prof John Rarity
• Prof Martin Cryan

Current projects

• Photonic crystal fibre sources of photon pairs
  • All fibre pair sources
  • All fibre quantum gates
  • Entangled states
• Study of microcavities based on III-V semiconductors for single photon sources and quantum information
  • Efficient single photon sources
  • Strong coupling in semiconductor microcavities
  • Exchanging information between spin and photons
• Diamond based single photon sources and quantum computing
• Developing integrated optics quantum gates
• Developing 3-D photonic crystal:
  • 3-D defect microcavities
  • control of spontaneous emission

The work is linked into a wider University research effort through links with:

• Centre for Nanoscience and Quantum Information
•  

Summary

New services such as broadband to every home streaming video and films on demand will dramatically increase the bandwidth required in our data and telecommunications networks. Optical fibre communications forms the backbone of all land based communications and as the bandwidth increases we require faster devices, switches and new systems concepts. Bristol research is contributing to this ever increasing requirement for bandwidth and flexibility through research into optical switch technology, wavelength conversion, high speed modulation, data regeneration and novel semiconductor lasers. We have the capability of testing systems at modulation speeds up to 40 Gb/s and with methods of aggregating channels to achieve throughput in excess of 1Tb/s over single fibres.

This activity has expanded into all-optical wavelength converters, high speed all-optical logic gates, optical bistability and multistability in semiconductor ring lasers optical waveguides and photonic structures in nonlinear optical materials such as LiNbO3.

Work on optical crosspoint switches has continued towards commercial exploitation with a pathfinder award. Interdisciplinary research into bio-photonics is also ongoing. Dr Martin Cryan has initiated a wireless-over-fibre effort integrating lasers and photodiodes with planar antennas to make transceivers for extending the coverage of WLANs. The group has acquired significant test equipment including a full 40Gbit/s bit error rate testing system.

Staff

• Prof Siyuan Yu
• Prof Judy Rorison
• Prof Martin Cryan

Current projects

• Integrated all-optical logic and memory using semiconductor ring lasers
• Optical switches:
  • Crosspoint switch development
  • integrated arrays of interferometric switches
• Wireless-Over-Fibre Systems
• Fibre optic sensors for intelligent dressings to improve chronic wound healing.

Summary

The Bristol Photonics Group have developed world-leading semiconductor laser and optical amplifier models and applied them to model quantum dot lasers and amplifiers, and in dilute nitride lasers. Experimental work has used the focused ion beam facility to post process lasers with detailed experimental characterisation.

We have adapted Bristol’s in-house Finite Difference Time Domain Code (FDTD) to 3-D simulation of optical structures and use this modelling expertise to design, fabricate (using FIBE) and characterise photonic crystal waveguides and single photon sources based on pillar microcavities. We have begun a study of tunable 3D colloidal photonic crystals for display purposes.

Our optical device fabrication and processing facility is key to a wide range of work within photonics group, but is also used University wide (electronics, materials science, biological science, physics, chemistry) and by external universities and industry.

Staff

• Prof Siyuan Yu
• Prof Judy Rorison
• Prof Martin Cryan
• Dr Peter Heard
• Prof Geoffrey Nash - Honorary Professor (University of Exeter)

Current projects

• Development of Quantum Dot Devices for Broad band Amplification
• Development of terahertz optical communications technologies
• Mid InfraRed LEDs, Lasers and detectors
• Vertical cavity Surface Emitting Lasers (VCSELs) for Advanced Communication (GWR fellowship)
• Focused Ion Beam based Photonic Crystal Fabrication
• Tunable 3D colloidal photonic crystals for display purposes.

The group is also involved in the University theme on  and Professor Rorison is the Electrical and Electronic Engineering representative.

Summary

The group is active in Solar Energy research and has a fully equipped solar cell lab with a solar simulator for recreating sunlight conditions in the lab and I-V curve tracer for characterising the efficiency of solar cells. We are interested in a number of emerging solar cell technologies such as Quantum Dot and Solar thermionic devices and are using advanced semiconductor physics and electromagnetic modelling tools to improve the efficiency of next generation devices.