Dr. Rupert Oulton is currently a Reader in the Department of Physics.
Dr. Oulton graduated with a PhD in physics from Imperial College London under the supervision of Prof. Gareth Parry FREng., with a focus on the physics of wavelength scale semiconductor optical devices. After graduation, Dr. Oulton investigated organic semiconductor optoelectronic materials with Prof. Donal Bradley FRS and went on to take a consultancy position with Mitsubishi Chemicals Advanced Research, where he developed enhancement layers for Organic Light Emitting Diode (OLED) flat panel displays. Dr. Oulton returned to academia as a Research Associate in Prof. Xiang Zhang's lab at UC Berkeley investigating the use of metals in optics to achieve light confinement significantly below the wavelength barrier and coordinating UC Berkeley’s Centre for Nano-Manufacturing. After winning an EPSRC Career Advancement Fellow he returned to the UK and took up a Leverhulme Lecturership in Plasmonic and Metamaterials at Imperial College London.
My research concerns the interaction of light with matter. Light being our primary means of sensing the world around us, means that our control over this fundamental interaction defines a broad applications base. Relevant existing technologies include bio-molecular sensing, optical data communications and data storage. Future and emerging technologies include quantum imaging, metrology, and quantum simulation/computing.
My team’s methodologies all involve squeezing light and matter into small regions of space for as long as possible. Keeping light “still” and localised makes it interact better with matter. E.g., an effective approach is to trap light between two highly reflective mirrors spaced by just a few mm – a microcavity. Such approaches work well for any type of interaction, but weaker, high-order (nonlinear) processes, are enhanced most dramatically. My interests are thus in phenomena such as Raman scattering (sensing and molecular fingerprinting) and non-linear optics (quantum states of light and photonics). A key goal is to make nonlinear effects as strong as linear ones, and exploit them in technologies.
Over the past decade I have been fascinated by metal optics. Metals do not simply reflect light; they also support optical excitations at their surfaces. These surface waves can focus light far smaller than any microscope objective – while the resolving power of a microscope is limited by light’s wavelength, metal nanostructures confine light to scales limited only by our nanofabrication tools! This research area is commonly called “plasmonics”.
Exploiting plasmonic effects in technologically relevant inorganic semiconductor materials (Silicon and III-V semiconductors) is an area where my contributions are internationally recognised. This could lead to faster and more compact switches and light sources to power future data communications, for example. Since semiconductors form the backbone of all electronic and optoelectonic systems, it is vital to exploit plasmonic effects with these materials.
Bose-Einstein Condensates of Light
Here we utilize optical microcavities to realise a new class of laser. Discovered in 2010, photon BEC is a laser regime where light and matter remain in thermal equilibrium. Unlike lasers, photon BECs can possess quantum correlations, making their light useful for metrology and communications. Currently my team is developing inorganic semiconductor photon BECs - a necessary step to application.
Non-linear Optical Metamaterials
Metamaterials are artificial media that exhibit optical responses not seen in natural materials. For example, metamaterials can "bend light the wrong way" by negative refraction, "electromagnetically cloak" objects from detection and even form "optical black holes". The capability to engineer the linear response of optical materials also extends to non-linear optical properties. Engineering artificial materials from their meta-atoms up to exhibit strong optical non-linearity provides new avenues in our ability to control light with light. We are using metal and dielectric nanostructures to realise strong and broad-band nonlinear processes.
As part of the UK’s quantum imaging hub, our Imperial team are developing a method of imaging with undetected photons. This applies conventional nonlinear optics in optical fibres and crystals alongside new nonlinear metamaterials. Funded by the UK’s quantum imaging hub till Nov 2024.
The joint reactive plasmonics programme, with King’s College London, explores heat at the nanoscale. The interplay of electrons and phonons as they share heat delivered by light has applications in localised heating, chemical catalysis and photo-detectors. Funded by Reactive Plasmoncis Grant till Jul 2021. New funding sought on optically addressed nano-magnet arrays for data storage and neuromorphic computing (collaborating with Branford/EXSS).
Plasmon lasers are a new class of laser. While conventional lasers are ideal for transfering light over large distances, plasmon lasers focus optical energy in both time and space to generate intense electric fields over small length and time scales. Light trapped within just ten billionths of a metre and lasting for just one trillionth of a second drastically alters the strength of light-matter interactions to vastly improve the sensitivity of conventional spectroscopies and the data capacity of optical communications.
Lawrence Berkeley Lab News: "Nanoscale waveguide for future photonics"
USNews: "Plasmon Lasers out of deep freeze"
IEEE Spectrum: "Nanolasers heat up"
MIT Technology Review: "Nanolasers heat up"
The Engineer: "Plasmon lasers pass commercial hurdle"
UC Berkeley News: "Nanolasers out of the deep freeze"
The Telegraph: "World''''s smallest laser"
NPR (US): "Scientists have big hopes for tiny lasers"
The Hindu: "World''''s smallest semiconductor laser"
Physics World: "Plasmonic laser puts the squeeze on light"
Laser Focus World: "Plasmons create the smallest laser"
EETimes: "Nanoscale lasers harness plasmons"
Journal Access Required:
MIT Technology Review: "Compressing Light"
Invited and Postdeadline Talks
“Lasers beyond the diffraction limit” 50th Anniversary of the Semiconductor Laser, University of Warwick, September (2012)
“Laser Science in a Nanoscopic Gap” ICNP, Beijing, China May (2012)
“Laser Science in a Nanoscopic Gap”, META, Paris, France April (2012)
“Laser Science in a Nano-scale Gap”, Photonics and Quantum Electronics, Utah, USA January (2012)
“Lasers Beyond the Diffraction Limit” CLEO, Baltimore, MD, USA May (2011)
“Coupling Molecular Photoluminescence Into Deep Sub-Wavelength Plasmon Waveguides.” CLEO/QELS, Baltimore, MD, USA May (2011)
“Lasers beyond the diffraction limit” IEEE Photonics Society Annual Meeting, Denver, CO, USA November (2010)
“Room Temperature Plasmon Lasers” CLEO/QELS, San Jose, CA, USA May (2010)
“Active plasmonics and nano-scale laser light sources” APS Spring Meeting, Portland, Oregon, USA, March (2010)
“Plasmonic Nano-Laser below the Diffraction Limit” Frontiers in Optics OSA Annual Meeting, San Jose, CA, USA October (2009)
“Giant Frequency-Pulling in Sub-Wavelength Plasmon Lasers” Frontiers in Optics OSA Annual Meeting, San Jose, CA, USA October (2009)
“A Sub-Wavelength Plasmonic Laser” SPIE Optics and Photonics, San Diego, California, USA, August (2009)
“Towards Sub-Wavelength Plasmonic Laser Devices” Integrated Photonics and Nanophotonics Research and Applications (IPNRA) Advanced in Optical Sciences, Honolulu, HI, USA, July (2009)
“Plasmonic nanowire lasers” 4th International Conference on Surface Plasmon Photonics (SPP4), Amsterdam, Netherlands, June (2009)
Lectures and Seminars
AMOLF Amsterdam, December (2012)
RIKEN, Japan, June (2012)
University of Sheffield, UK March (2012)
ESPCI, University Paris-Sud, France April (2011)
University of Birmingham, Birmingham, UK April (2011)
Seminar Institute for Solid State Physics, University of Jena, Jena Germany Friday 11th February (2011)
Physics Department, Imperial College London, UK Thursday June 10th (2010)
Seminar UC Berkeley Dept. of Electrical and Computer Engineering, Berkeley, CA, USA Friday 7th November (2008)
Lectures: Solid State Physics
Lectures: Optical Communications
Head of Experiment: 3rd Year Lab
Tutorials - 2nd Year.
Lecture course: "Advanced Topics in Plasmonics"
Emma Pearce - Quantum Imaging
John Yang - Quantum Imaging
Nicholas Gusken - Silicon Plasmonics
Paul Dichtl - Nonlinear metamaterials
Monica Mota - Reactive Plasmonics
et al., 2021, Tunable double epsilon-near-zero behavior in niobium oxynitride thin films, Applied Surface Science, Vol:569, ISSN:0169-4332, Pages:150912-150912
et al., 2021, Hot electron physics and applications, Journal of Applied Physics, Vol:129, ISSN:0021-8979
et al., 2021, Learning the Fuzzy Phases of Small Photonic Condensates, Physical Review Letters, Vol:126, ISSN:0031-9007
et al., 2021, Special Topic: Quantum sensing with correlated light sources, Applied Physics Letters, Vol:118, ISSN:0003-6951
et al., 2021, Critical coupling of a single metallic nanoantenna under focused illumination