Photonics Group AR Adams, J Allam, K Homewood, TJC Hosea, D Lancefield, BN Murdin (Group Leader), G Reed, S Sweeney Advanced Technology Institute, School of Electronics and Physical Sciences, University of Surrey, Guildford, GU2 7XH III-V Semiconductor Light Emitters Significant Achievements The University of Surrey was awarded the Queen's Anniversary Prize in 2002 for the work of Professors Adams (pictured left) and Sealy of the ATI. Collaborating with industry we have made break-throughs in the development of devices which have now become ubiquitous, such as the strained-layer quantum well laser. Light emitters made from gallium nitride, and related alloys give all the colours of the rainbow and white besides (with CRHEA, France). Projects Gallium nitride light emitters for displays and lighting (3 patents applied for) Mid-infrared gas sensing lasers containing antimony and nitrogen Higher-speed, higher-power lasers for information technology Vertical emission lasers for optical fibre communications Facilities High Pressure is a very useful tool for physics and materials science: in semiconductors it affects nearly all important properties including the energy of the emitted light. It gives an insight into the inner workings of the semiconductor laser. Our systems can apply up to half a million atmospheres and determine the impact on electrical and optical properties of the device Specialist spectroscopy for non- destructive optoelectronic wafer testing (from UV to IR) as an industrial tool Our reflectance and photoluminescence laboratory showing the different laser sources that can be used for probing the samples Motivation High (THz) bandwidth light sources are needed for IT New wavelengths from UV to THz (far-IR) are needed for a host of new sensing applications High efficiency emitters are needed for energy saving and long-life displays and lighting Silicon Photonics A silicon Bragg grating interrogation system using MEMS and optical circuits (picture in collaboration with BAE Systems) Significant achievements Light emission from silicon Dislocation engineering in silicon (patented ULSI-compatible technology), published in NATURE Semiconducting silicides (iron disilicide). First serious silicon based LED, published in NATURE (patented technology). Amorphous iron disilicide (a new semiconductor discovered by us): applications expected to be for a new sustainable solar cell technology. Research towards the first silicon injection laser diode. Spin-out: Si-light Technologies Ltd, a start- up company set up to exploit our silicon light emission technologies. Significant achievements Silicon optical waveguides Dual grating-assisted directional coupling between fibres and thin semiconductor waveguides Intel sponsorship of 2 students New grating assisted optical couplers (UK patent). New process for “Arrayed Waveguide Grating” optical multiplexers (UK patent) Silicon-on-insulator (SOI) photonics including MHz and GHz frequency Optical Phase Modulators and optical racetrack resonators Cross section of SOI waveguide and its mode profile for quasi-TE and -TM polarisations SEM image showing the side view of 1 st order Bragg grating with grating period of 227nm and grating etch depth of 130nm Motivation Cheap and efficient silicon-based light emitters are needed for integration with CMOS, with applications to all-silicon optical communications (Fibre to the Home etc). Silicon waveguides and high speed modulators are needed for optical interconnects in microelectronics. This technology has come of age with recent new achievements. Femtosecond dynamics Facilities Advanced amplified femtosecond lasers Intense ultrashort (50 fs) pulses from UV to THz ‘FELIX’ free electron laser in Utrecht mid- to far-infrared picosecond pulsed source complementing Surrey lasers Projects Dynamics of semiconductor lasers THz dynamics of excitons Spin dynamics of narrow gap materials Motivation Optical information systems will soon need to operate with Terabit/s bandwidth, switching light pulses on a sub-picosecond time-scale. Dynamical systems (i.e. those that do useful work) that involve electronic, vibrational and optical properties of photonic materials are controlled by processes occurring on time- scales as short as femtoseconds Dynamics of charge transfer is a key issue in hybrid and composite nanoscale materials Bright pulse Dark pulse Relaxation period Round-trip time Femtosecond pulses circulating in a semiconductor laser cavity reveal the inner workings of optical gain Time (picoseconds) frequency Simulation of ultrashort pulse propagation in semiconductor lasers New directions Hybrid narrow gap / ferromagnet spintronic devices Ultra-fast spectroscopy under pressure Nanotube Nonlinear Waveguides for Next Generation Electrophotonics New photonic crystals with switchable optical transmission, including novel inverse opals from German Polymer Institute Precise material modification (direct writing) using high intensity femtosecond pulses Optical sensors and solar cells using organic / semiconductor hybrids and composites (collaboration with Nano-Electronics Centre) Electron spins in InAs semiconductor are all aligned upwards by a femtosecond pulse. The spins then precess around a magnetic field, while relaxing. Significant Achievements First coherent spin manipulation in small bandgap / high spin-orbit coupling materials at room temperature (see fig below), published in Physical Review First measurements of picosecond relaxation in silicon/germanium quantum cascade structures published in Physical Review New directions Bio-molecule sensors New dilute-nitride avalanching photodetectors with ultra-high sensitivity (patent applied for) Professor Adams in the high pressure facility Defect engineering of sulphur in silicon for light emission at long wavelength 1.5  m 1.3  m Light Heat lasing energy normalised threshold current High pressure tunes the wavelength of laser emitters and shows that infrared lasers produce more heat than light H h=rH D W SiO 2 Si Air