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Jason Smith

Professor Jason Smith
Professor of Photonic Materials and Devices

Department of Materials
University of Oxford
16 Parks Road
Oxford OX1 3PH

Tel: +44 1865 273780 (Room 195.30.10)
Tel: +44 1865 273777 (reception)
Fax: +44 1865 273789 (general fax)

Photonic Nanomaterials Group

Summary of Interests

Leader of the Photonic Nanomaterials Group (PNG) in which research is focused on optical and electronic properties of solid state nanostructures for applications such as optoelectronics devices, quantum information processing and photovoltaics. At present the Group’s research involves two such systems - semiconductor nanocrystals and colour centres in diamond which we investigate using luminescence-based optical techniques. More information about our research can be found in the project descriptions below, or on the PNG website.

Current Research Projects

High Q optical microcavities for solid state cavity QED
P. Dolan, Dr. G. Hughes, Dr. J.M. Smith
In this project we are developing large arrays of high quality tunable optical microcavities and using them to modify the photon emission properties of nanomaterials such as diamond colour centres and semiconductor nanocrystals. The project focuses on the basic science of the emitter/cavity quantum systems, and explores their use as single photon sources, microlasers, and in a range of sensing and spectroscopic applications. Collaborators include the University of Strathclyde, the University of Bristol, and the University of Melbourne.

Enhancing the efficiency of thin film solar cells using optical confinement
M. Wincott, A. Powell, Dr. H.E. Assender, Dr. A.A.R. Watt, Dr. J.M. Smith
Thin film solar cells offer an inexpensive means to generate clean energy, but current efficiencies are limited to around five percent, about three times lower than commercial polycrystalline silicon cells. One of the main reasons behind the low efficiency is that a tension exists between the desire to absorb as much as possible of the incident light, in which case the optical path length should be thick (at least several hundred nanometres), and the desire to extract the photogenerated charge carriers efficiently from the cell, in which case the exciton transport path length should be short (no more than a few tens of nanometers). Most attempts to solve this problem involve using a thick cell, and focusing the advanced aspects of cell design on building in some means for ensuring a short transport path length. Here we take the opposite viewpoint; that the optical path can be elongated for a given cell geometry by the use of wave guiding and cavitation, thereby reducing the burden placed on the transport related features of the device. This new project involves the design, fabrication, and testing of devices that explore this theme by employing inexpensive approaches to encourage light to propagate in the plane of the film.

Roll-to-roll processing of organic electronics
Dr G.A.W. Abbas, Z. Ding, Dr. H.E. Assender
Electronics components that can be manufactured using roll-to-roll processing offer the possibility of lower cost devices as well as those that might be mechanically flexible in use.  Roll-to-roll (R2R) processing, using a flexible substrate (typically a polymer film) allows for cheap production of many components very rapidly, with low energy requirements.  Key areas of exploitation of this technology include flexible displays, but there is also a wealth of lower-cost applications. Tagging and tracking of fast moving consumer goods is an example technology that truly exploit the very low-cost nature of the production and in which the manufacturing is closely linked to the manufacturing routes currently exploited for e.g. packaging technologies.  This project seeks to exploit the existing industrialised technology of vacuum R2R processing, widely used for example in the packaging industry, to develop the manufacture of very low cost organic field-effect transistor (OFET)-based devices and circuits.  This manufacturing route, like solvent based systems, is cheap and provides flexible product, and we can exploit high electrical mobility molecular semiconductors. Additional advantages of the solvent-free vacuum processes include: a) likely enhanced web-speed, b) integration with vacuum-based metal deposition for conducting channels, and metal or ceramic deposition for barrier layers and possible interfacial modification, and c) the ability to deposit multiple thin layers to build up device structures without solvent interactions with underlying layers.  The project will exploit our existing R2R web processing facility to explore the principal manufacturing challenges to R2R vacuum production of OFET devices: 1) selection and adaptation of materials to vacuum deposition integrated with design of suitable circuitry, 2) patterning of the semiconductor and insulator layers to allow the formation of circuit connections between devices and 3) reliability of manufacture to be able to produce arrays of multiple transistors for circuits.  It will allow us to explore and develop the deposition of molecular semiconductor and dielectric materials and then the subsequent reliability and thermo-mechanical resilience of the resulting product such that it might need to withstand, for example, during a lamination process.

3 public active projects

Research Publications


P. R. Dolan, G. M. Hughes, F. Grazioso, B. R. Patton, and J. M. Smith, Femtoliter tunable optical cavity arrays, Optics Lett. (in press).

F. Grazioso, B. R. Patton, and J. M. Smith, A high stability beam-scanning confocal optical microscope for low temperature operation, Review of Scientific Instruments 81, (2010).

C. A. Cattley, A. Stavrinadis, R. Beal, J. Moghal, A. G. Cook, P. S. Grant, J. M. Smith, H. E. Assender, and A. A. R. Watt, Colloidal synthesis of lead oxide nanocrystals for photovoltaics, Chem. Comm. 46, 2802 (2010).

R. M. Beal, A. Stavrinadis, J. H. Warner, J. M. Smith, H. E. Assender, and A. A. R. Watt, The molecular structure of polymer-fullerene composite solar cells and its influence on device performance, Macromolecules 43, 2343 (2010).

A. Stavrinadis, J. M. Smith, C. A. Cattley, A. G. Cook, P. S. Grant, and A. A. R. Watt, SnS/PbS nanocrystal heterojunction photovoltaics, Nanotechnology 21, 185202 (2010).

A. Stavrinadis, S. Xu, J. H. Warner, J. Hutchison, J. M .Smith and A. A. R. Watt, Superstructures of PbS nanocrystals in a conjugated polymer and the aligning role of oxidation, Nanotechnology 20, 445608 (2009).

D. J. Keeble, E. A. Thomsen, A. Stavrinadis, I. D. W. Samuel, J. M. Smith, and A. A. R. Watt, Paramagnetic point defects and charge carriers in PbS and CdS nanocrystal polymer composites, J. Phys. Chem. C 113, 17306 (2009).

S. C. Benjamin, B. W. Lovett, and J. M. Smith, Prospects for measurement based quantum computing using solid state spins, Laser & Photonics Reviews, 3, 556 (2009).

P. K. Santra, R. Viswanatha, S. Daniels, N. L. Pickett, J. M Smith, P. O'Brien and D. D. Sarma, Investigation of the internal heterostructure of highly luminescent quantum dot - quantum well nanocrystals, J. Am. Chem. Soc. 131, 470 (2009).

B. A. Fairchild, P. Olivero, A. D. Greentree, F. Waldermann, R. A. Taylor, J. M. Smith, S. Rubanov, S. Huntington, B. Gibson, D. N. Jamieson, and S. Prawer, Fabrication of ultra thin membranes from single crystal diamond for photonic and NEMS applications, Advanced Materials 20, 4793 (2008).

A. Stavrinadis, R. Beal, J. M. Smith, H. E. Assender, and A. A. R. Watt, Direct formation of PbS nanorods in a conjugated polymer, Advanced Materials 20, 3105 (2008).

S. H. Kim, P. H. Sher, Y. B. Hahn, and J. M. Smith, Luminescence from single CdSe nanocrystals embedded in ZnO thin films using atomic layer deposition, Nanotechnology 19, 365202 (2008).

P. A. Dalgarno, J. M .Smith, J. MacFarlane, B. D. Gerardot, K. Karrai, A. Badolato, P. M. Petroff, and R. J. Warburton, Coulomb interactions in single charged self-assembled quantum dots: Radiative lifetime and recombination energy, Phys. Rev. B 77, 245311 (2008).

P. A. Dalgarno, M. Ediger, B. D. Gerardot, J. M. Smith, S. Seidl, M. Kroner, K. Karrai, P. M. Petroff, A. O. Govorov, and R. J. Warburton, Optically induced hybridization of a quantum dot state with a filled continuum, Phys. Rev. Lett. 100, 176801 (2008).

P. H. Sher, J. M. Smith, P. A. Dalgarno, R. J. Warburton, X. Chen, P. J. Dobson, S. M. Daniels, N. L. Pickett, and P. O'Brien, Power law carrier dynamics in semiconductor nanocrystals at nanosecond time scales, Appl. Phys. Lett. 92, 101111 (2008).

S. Seidl, M. Kroner, P. A. Dalgarno, A. Hogele, J. M. Smith, M. Ediger, B. D. Gerardot, J. M. Garcia, P. M. Petroff, K. Karrai, and R. J. Warburton, Absorption and photoluminescence spectroscopy on a single self-assembled charge-tunable quantum dot, Phys. Rev. B 72 195339 (2005).

P. A. Dalgarno, J. M. Smith, B. D. Gerardot, A. O. Govorov, K. Karrai, P. M. Petroff, and R. J. Warburton, Dark exciton decay dynamics of a semiconductor quantum dot, Phys. Stat. Solid. A-Applications and Materials Science 202 p.2591-2597 (2005).

A. J. Moore, J. Smith, and N. J. Lawson, Volume three-dimensional flow measurements using wavelength multiplexing, Optics Lett. 30, p.2569 (2005).

J. M. Smith, P. A. Dalgarno, R. J. Warburton, A. O. Govorov, K. Karrai, B. D. Gerardot and P. M. Petroff, Voltage control of the spin dynamics of an exciton in a semiconductor quantum dot, Phys. Rev. Lett. 94, 197402 (2005).

M. Ediger, P. A. Dalgarno, J. M. Smith, B. D. Gerardot, R. J. Warburton, K. Karrai and P. M. Petroff, Controlled generation of neutral, negatively-charged and positively-charged excitons in the same single quantum dot, Appl. Phys. Lett. 86, 2119209 (2005).

B. Urbaszek, E. J. McGhee, J. M. Smith, R. J. Warburton, K. Karrai, B. D. Gerardot, J. M. Garcia and P. M. Petroff, Charged excitons in individual quantum dots: effects of vertical electric fields and optical pump power, Physica E 17, 35 (2003).

J. M. Smith, P. A. Dalgarno, B. Urbaszek, E. J. McGhee, G. S. Buller, G. J. Nott and R. J. Warburton, Carrier storage and capture dynamics in quantum-dot heterostructures, Appl. Phys. Lett. 82, 3761 (2003).

M. A. Malik, P. O'Brien, S. Norager and J. Smith, Gallium arsenide nanoparticles: synthesis and characterisation, J. Mater. Chem. 13, 2591 (2003).

J. M. Smith, G. S. Buller, D. Marshall, A. Miller and C. C. Button, Microsecond carrier lifetimes in InGaAsP quantum wells emitting at lambda=1500 nm, Appl. Phys. Lett. 80, 1870 (2002).

J. M. Smith, P. A. Hiskett, I. Gontijo, L. Purves and G. S. Buller, A picosecond time-resolved photoluminescence microscope with detection at wavelengths greater than 1500 nm, Rev. Sci. Instrum. 72, 2325 (2001).

J. M. Smith, P. A. Hiskett and G. S. Buller, Picosecond time-resolved photoluminescence at detection wavelengths greater than 1500 nm, Opt. Lett. 26, 731 (2001).

P. A. Hiskett, J. M. Smith, G. S. Buller and P. D. Townsend, Low-noise single-photon detection at wavelength 1550 nm.Electron. Lett. 37, 1081 (2001).

S. Pellegrini, G. S. Buller, J. M. Smith, A. M. Wallace and S. Cova, Laser-based distance measurement using picosecond resolution time-correlated single-photon counting, Meas. Sci. Technol. 11, 712 (2000).

P. A. Hiskett, G. S. Buller, A. Y. Loudon, J. M. Smith, I. Gontijo, A. C. Walker, P. D. Townsend and M. J. Robertson, Performance and design of InGaAs/InP photodiodes for single- photon counting at 1550 nm, Appl. Optics 39, 6818 (2000).

Projects Available

Engineering nitrogen-vacancy centres in diamond using laser writing
Jason Smith (Materials) with Patrick Salter and Martin Booth (Engineering Science)

Colour centres in diamond offer excellent prospects for the development of scalable solid state quantum computers. In recent years the combination of spin coherence and optical coherence in nitrogen-vacancy (NV) centres has resulted in a range of milestone demonstrations including local error correction and entanglement across a network large enough to demonstrate loophole-free violation of Bell’s inequality. The development of advanced devices using NV centres has however been limited by the inability to position high quality centres on-demand in a diamond crystal.

Over the past three years we have pioneered novel laser-writing methods for the fabrication of single NV centres that provides a solution to this problem. Laser writing allows NV centres to be created in diamond with a positioning accuracy of order 100 nm and with excellent coherence properties. The work offers a clear route to the realisation of chip-scale devices containing many thousands of qubits which could facilitate the first universal fault-tolerant quantum processors.

This project will focus on a critical element of the engineering of single NV centres using laser writing, namely the ability to perform local annealing with a laser to modify the crystal environment around a written NV centre and control its properties. Initial proof-of-concept experiments have shown that the basic idea works but a number of important questions remain regarding the degree of control that can be achieved. The goal of the project will be to answer these questions by performing systematic studies of the effect of local annealing on defect concentrations and local strain, plus the creation of multiple NV centres coupled by spin-spin interaction and the deletion of unwanted NV centres at a chosen site.

You will work within a team of researchers in Oxford developing the laser writing methods and other aspects of the emerging device technology, in collaboration with researchers at the universities of Warwick, Cambridge and Strathclyde. The team forms part of the UK Quantum Technologies Hub in Networked Quantum Information Technologies (NQIT), providing a vibrant and interdisciplinary community spanning ten universities, with research into multiple hardware platforms plus theoretical and engineering efforts aimed at developing scalable quantum computers. The project is funded by full studentship associated with the quantum technology programme.

This NQIT hub EPSRC-funded 3.5-year DPhil in Materials studentship will provide full fees and maintenance for a student with home fee status (this includes an EU student who has spent the previous three years (or more) in the UK undertaking undergraduate study).  Candidates with EU fee status are eligible for a fees-only award, but would have to provide funding for their living costs from another source such as personal funds or a scholarship.  The stipend will be £14,777 per year.  Information on fee status can be found at

Individual applications will be considered as and when they are received and this position will be filled as soon as possible.

Questions concerning the project can be addressed to Professor Jason Smith (  General enquiries on how to apply can be made by e‑mail to  You must complete the standard Oxford University Application for Graduate Studies.  Further information and an electronic copy of the application form can be found at

Also see homepages: Jason Smith

Defects in diamond as spin qubits in quantum networks
Prof Jason Smith

Diamond has unsurpassed properties for quantum technologies such as quantum sensing and quantum computing, and point defects in the material can act as trapped atoms with properties ideal for the storage and manipulation of quantum states. A major challenge is the efficient coupling of these atom-like systems with optical systems, so that quantum states can be transferred between electrons (or nuclei) and photons to enable the construction of scalable networks. This doctoral project will involve the coupling of single nitrogen-vacancy defects in diamond to optical microcavities in order to maximise the efficiency of quantum state transfer and facilitate scalable networking. You will be part of a small team working towards this goal, which will involve a range of techniques including optical characterisation and spectroscopy, fabrication and handling of diamond microstructures and optical devices, and lasers and cryogenic instrumentation. As such the project is well suited to an energetic and hands-on student who enjoys building apparatus and has a good working knowledge of optics. The project is part of a substantial nationwide program to build scalable quantum networks involving matter systems and photons.

Also see homepages: Jason Smith

Sensing, characterisation and manipulation at the nanoscale using optical microcavities
Prof Jason Smith and Dr Aurelien Trichet

Optical sensing and spectroscopy are powerful tools for detecting and characterising nanoparticles at the single particle level. Pollutants and aerosols or microbiological organisms such as viruses have characteristic optical signatures based on their refractive index, size, and polarisability as well as spectral signatures that allow them to be identified and studied. This project will develop novel optical microcavities as means of confining light such that its interaction with nanoparticles is both strengthened and highly controlled. These microcavities show great potential for the trapping and manipulation of particles, and for particle identification using refractive index and spectroscopic methods. The project will involve fabrication of cavity devices and using them to perform some foundational experiments in this area. The student project is part of a larger effort within the group, in collaboration with Dr Claire Vallance in the Department of Chemistry. 

Also see homepages: Jason Smith

Spectroscopy and device applications of monolayer semiconductors coupled to optical microcavities
Prof Jamie Warner, Prof Jason Smith

Monolayer semiconductor materials such as WS2 and MoSe2 display strong optical transitions that are attractive for nanoscale optoelectronic devices. These properties can be both enhanced and harnessed by coupling the materials to optical microcavities, opening possibilities for fast optical switches, ultra-low threshold lasers, and advanced quantum light sources. This project brings together the expertise of two leading research groups in 2D materials (Prof Jamie Warner) and in microcavity photonics (Prof Jason Smith). The project will build on some preliminary work which provides first demonstrations of basic phenomena, and will develop the experiments further to investigate ‘strong coupling’ (ie the creation of polaritons - part electronic excitation, part photon) and the switching of polariton states to realise ambient temperature devices.

Also see homepages: Jason Smith Jamie Warner

Also see a full listing of New projects available within the Department of Materials.