Our group is collaborating with more than 40 partners across Europe and the UK, through several multi-disciplinary projects involving high-tech industries, research centres and universities. 

Partners' location of externally funded collaborations

EU projects:
Network of Excellence: Nanophotonics for Energy Efficiency: 2010-2013
The Nanophotonics for Energy Efficiency aims to create a virtual centre of excellence to reorient and focus nanophotonics research towards the challenges in energy efficient applications. The network clusters nanophotonic laboratories and research groups in Europe combining their expertise in the development of disruptive approaches to lighting and solar cell technology. The consortium consolidates know-how and resources of 9 different institutions in 6 European countries with complimentary research and development expertise, integrating more than 130 scientists, engineers, technicians and managers in nanophotonics.

Project partners:
1. Institut de Ciències Fotòniques, Spain
2. Technische Universitaet Dresden, Germany
3. University of Southampton, UK
4. Commissariat Energie Atomique, France
5. Laboratorio Europeo Di Spettroscopie Non Linear, Italy
6. Consejo Superior De Investigaciones Cientificas, Spain
7. Bilkent University, Turkey
8. Kungl Tekniska Högskolan, Sweden
9. Universitat Politecnica De Catalunya, Spain

ITN-Icarus:2010-2013
Our key aim is to develop hybrid semiconductor materials that support entirely new optical states. In many cases, such excitations arise from a direct hybridization of organic and inorganic states using a confined cavity-photon to ‘mediate’ the excitations. Such systems will necessarily have optical and electronic properties that cannot be found in either material system alone. We believe that this will permit us to develop materials having entirely new applications in photonics, electro-optics and photovoltaics. Our methodology is distinctly different to work performed on the development of semiconductor materials for optoelectronics.  Here, the vast majority of research has centered on the development of technologies based largely on organic or inorganic semiconductors. This division of effort has established two parallel yet largely non-interacting research communities. The establishment of ICARUS is in direct response to this division of effort, with the central goal of our network being methods to control energy transfer in hybrid semiconductor systems, driven by the desire to create new types of light emitting devices (LEDs), lasers, photodetectors, and photovoltaics.

Project partners:
1. University of Sheffield, Physics and Astronomy
2. Foundation for Research and Technology Hellas, Institute of Electronic Structure and Laser
3. IBM Ltd., Zurich Research Lab 
4. Scuola Normale Superiore di Pisa, Classe di Scienze   
5. Politecnico di Milano, Physics Department   
6. Imperial College, Department of Physics 
7. Ludwig Maximilians University of Munich, Department of Physics   
9. University of Southampton, Department of Physics  

ITN-Spinoptronics:2009-2013
Spin-optronics is a new emerging research area, which combines studies of spin and optical polari-sation effects in solids with the ultimate goal of creating quantum optoelectronic devices. This is an interdisciplinary research field at the crossroads of fundamental physics of quantum-mechanical spin, optoelectronics, and nano-technology. Most of the recent developments in spin-optronics and prospects for future applications are based on the last decade’s spectacular progress in nanotech-nology. Quantum confinement of the particle motion in one or more directions drastically changes the spin-orbit interaction and correspondingly all spin properties. All three main themes of the Network research activities – growth & technology, spectroscopy and theory - are concentrated on novel spin and light polarisation effects in nanostructures, taking advantage of con-finement of not only charges and spins, but also photons.

Project partners:
1. University Blaise Pascal, LASMEA
2. CNRS&University Joseph Fourier, Institut Neel  
3. INSA-CNRS-UPS, LPCNO   
4. University of Sheffield, Dept of Physics and Astronomy  
5. University of Southampton, School of Physics and Astronomy   
6. University of Exeter, School of Physics   
7. Toshiba
8. Ioffe Institute, Center of Nanoheterostructure
9. Universidad Autónoma de Madrid, Física de Materiales y Física Teórica de la Materia Condensada
10. Dortmund University, Experimental Physics

ITN-CLERMONT-4:2009-2013
The primary goal of the CLERMONT4 network is to facilitate the exploitation of the breakthroughs in polaritonics which occurred in 2006-2008 by leading European industrial groups. To exploit the huge potential of polaritonics, we are planning to educate and train a new generation of physicists and device engineers able to conduct research and its application in this new area and to implement the ambitious theoretical concepts of polariton devices in practice. We shall focus on realisation of four prototypes of polariton devices: electrically pumped polariton lasers, micron size optical parametric oscillators, optical logic gates and cavity-based emitters of entangled photonic pairs. These devices would open a new époque in optoelectronics bringing quantum coherent effects into the everyday life. In order to realise these goals we have built a consortium of academic teams which have already given to Europe an enormous lead in the international competition with American and Japanese groups to realize practical polariton devices. Furthermore, we bring these academic teams together with an outstanding group of industrial partners capable of effectively driving through the translation of emerging promising new physical demonstrations into devices.

Project partners:
1. University of Rome II, Physics department
2. Centre National de la Recherche Scientifique, Délégation de Languedoc Roussillon
3. Universite Paris VI, Ecole Normale Supérieure
4. University of Sheffield, Physics and Astronomy Department
5. University of Southampton, Physics and Astronomy Department
6. University of Cambridge, Cavendish Laboratory
7. Durham University, Department of Physics
8. Universidad Autónoma de Madrid, Depts. Física de Materiales y Física Teórica de la Materia Condensada
9. Foundation for Research and Technology - Hellas, Institute of Electronic Structure & Laser
10. Ecole Polytechnique Fédérale de Lausanne, Institut de Photonique et d’Electronique Quantiques

EPSRC projects
:

Engineering polariton non-linearity in organic and hybrid-semiconductor microcavities: 2010-2013
Strongly-coupled microcavities are a fascinating system for the exploration of the fundamental physics of the interactions between light and matter. Under such circumstances, the emissive states in such microcavities are termed 'polaritons', and can be described as an admixture between an exciton and a confined cavity photon. The optical properties of polaritons can be very different from their constituent parts (excitons and cavity photons), and thus there is a significant opportunity to explore new fundamental processes, and develop new types of devices that may find applications as low-threshold lasers, optical-amplifiers and high-speed optical switches.

At present, the majority of work done on the strong-coupling regime in microcavities has centred on structures that contain inorganic semiconductors (either III-V, II-VI or GaN based materials). We have however pioneered the study of strong-coupled microcavities containing organic (carbon-based) semiconductors, which are anticipated permit new effects to be engineered. Despite the importance of organic-semiconductors in a range of optoelectronic devices (LEDs, photovoltaics, FETs, lasers etc) relatively little is understood regarding the microscopic processes that occur in strongly-coupled organic microcavities.

Development of a basic understanding of non-linear processes and properties of organic-semiconductors in strongly-coupled microcavities will thus be a key area that we will address in this project. Key components of the research include studies the interactions between organic-polaritons and vibrational modes of the molecular semiconductor and the generation of organic exciton-polaritons at high density following electrical injection of carriers. We will also explore the fabrication and optical properties of 'hybrid-semiconductor' microcavities and devices (containing organic and inorganic semiconductors), and will study optically-driven energy-transfer between the different types of excitation using both linear and ultra-fast measurements.

We are confident that our work will provide new fundamental insights into the optical properties of organic-polaritons (including relaxation and condensation), the transfer of excitations between different semiconductor materials via a cavity photon over large distances (> 100 nm) and the generation of new electrically-driven polariton devices. We believe that we are in an excellent position to undertake such an ambitious programme of research due to our world-leading expertise in strongly coupled organic semiconductor microcavities (Sheffield), and two-colour ultra-fast spectroscopy of microcavities (Southampton).

Project partners:
University of Sheffield
University of Southampton
Cambridge Display Technology Ltd

Femtosecond semiconductor lasers: 2009-2012
The aim of this proposal is to demonstrate for the first time a semiconductor laser emitting transform-limited optical pulses of less than 200 fs duration in a diffraction-limited beam. This achievement will open the way for the development of truly compact ultrafast optical systems. Our device is a surface-emitting laser, optically pumped using the cheap and rugged technology developed for diode-pumped solid state lasers, with perfect beam quality enforced by an extended cavity. It emits a periodic train of ultrashort pulses at a repetition rate of a few GHz using the optical Stark effect passive mode-locking technique introduced by the Southampton group. Recent proof-of-principle experiments have shown that these lasers can generate stable 260-fs pulse trains. We have shown, moreover, by modelling and by experiment, that the optical Stark mechanism can shorten pulses down to durations around 70 fs, comparable with the quantum well carrier-carrier scattering time. Our proposal is to build on these world-leading results with a systematic exploration of the physics of lasers operating in this regime. The key is to grow quantum well gain and saturable absorber mirror structures in which dispersion, filtering and the placing of the quantum wells under the laser mode are controlled to tight tolerances. We shall achieve this using molecular beam epitaxy to realise structure designs that are developed with the aid of rigorous numerical modelling of the optical Stark pulse-forming mechanism. We shall also use femtosecond pump and probe spectroscopy to determine the dynamical behaviour of our structures in this regime directly. For these pioneering studies, the compressively-strained InGaAs/GaAs quantum well system operating around 1 micron is most suitable; and this is where we shall work; however, the devices that we develop can in principle in future be realised in other material systems in different wavelength regions. We shall also make a first study of incorporating quantum dot gain and absorber material into optical Stark mode-locked lasers, aiming to exploit the intrinsically fast carrier dynamics of these structures. In summary, this proposal aims to shrink femtosecond technology from shoebox-size to credit-card size, and in the process explore a regime of ultrafast semiconductor dynamics that has never before now been exploited to produce light pulses.

Project partners:
University of Cambridge
University of Nottingham
University of Southampton
Fianium Ltd

Spin currents and superfluidity of microcavity polaritons: 2008-2012
The overall goal of the project is to detect experimentally exciton-polariton superfluids and spin currents in microcavities and to develop a full quantum theory of exciton-polariton superfluidity. The fingerprints of polariton superfluidity will be searched for in spatially- and directionally-resolved optical measure-ments with spectral, temporal and polarization-detection, with or without application of external magnetic fields, on improved quality strain free microcavity samples. We shall look for conventional and superfluid polariton spin currents in the regime of the optical spin Hall effect. We expect theoretically important dif-ferences between polariton and conventional superfluids caused by a peculiar dispersion and spin structure of exciton-polaritons. We aim to study theoretically and experimentally the polarization dynamics of both resonantly and non-resonantly excited polariton condensates to reveal the specifics of polariton superfluid-ity and search for new effects including the optical spin-Hall effect and the spin analogue of the Meissner effect.

Project partners:
Cardiff University
University of Southampton

Actively manipulating electronic excitations in nanocrystals: 2007-2011
Colloidal nanocrystals made of semiconductor materials resemble fluorescent beads that are only a few nanometres in diameter. Their optical emission properties can be tuned from ultraviolet to infrared wavelengths by suitably choosing the material and adjusting their size and shape. To date, nanocrystals have been exploited in areas ranging from genomic and proteomic bio-assays, cell-staining and high-throughput screening, where they serve as fluorescence markers and more applications have been envisaged in LEDs, lasers, optical switches, photovoltaics, data storage devices, catalysis, drug delivery and other biomedical assays. Compared to self-assembled quantum dots made by molecular beam epitaxy, colloidal nanocrystals can be produced by comparatively simple and inexpensive solution methods, and are freely suspended in a solvent or matrix, while retaining a high optical and electronic stability. The precisely controlled size and shape of nanocrystals, such as in quantum dots, rods or even tetrapods, renders them promising building blocks for nanoscience and nanotechnology. Furthermore, shape control in the synthesis of colloidal nanocrystals offers unprecedented abilities to tune the interaction of solid state quantum structures with the environment, opening up the possibility of performing nanoscale manipulations of the optical and electronic properties. This 'First Grant' proposal aims for key experimental studies on the fundamental properties of colloidal nanocrystals. The overall plan is to develop novel applications based on the active manipulation of the optoelectronic properties of nanocrystals and on self-assembly methods for their alignment in large array device configurations. The ultimate applications range from electric-field nanosensors, single photon tunable sources to optical memory elements and all optical parallel processing.

Other:

Hybrid LEDs: 2010-2012, funding body Swedish Research Council
Project partners:
University of Linkoping
University of Southampton

Optical techniques for underwater environmental monitoring: 2010, funding body University of West Indies

Project partners:
University of West Indies, Barbados
University of Southampton

New apparatus for the manipulation and characterization of spin through strain: 2008, funding body JSPS
The aim of this project was to develop methods for control and manipulation of electron spin dynamics in GaAs/AlGaAs quantum well structures by externally applied perturbations, principally strain. The importance of this is that it tests our fundamental understanding of the mechanisms of spin evolution and relaxation and will lead to methods for voltage gate control of electron spin which will be central to applications in spintronics. 

Project partners:
Hokkaido University
University of Southampton