PHOTONICS GROUP OPEN DAY AND LAB TOURS
Wednesday 30th January 2013, Room 630, Blackett Laboratory
Introduction to MRes in Photonics: 2.00pm
Introduction to PhDs in Photonics: 2.30pm
Refreshments: 4.30pm-5.30pm
Thank you for your interest in the Photonics Group. This handout is designed to give a short summary of the
MSc and PhD opportunities within the group and to provide links to other relevant information. For more
information please visit our website http://www3.imperial.ac.uk/photonics or contact
photonics@imperial.ac.uk
PHD STUDENTSHIPS IN THE
PHOTONICS GROUP
Each year the Photonics Group recruits up to ~10
research students for a variety of different
projects, supported by a range of sponsors. In
general, we expect our research students to
undertake a four year MRes+PhD programme. The
MRes course runs for one year and entails a term
of lectures and practical work in optics and
photonics (alongside the MSc in Optics and
Photonics) followed by a 9 month MRes project
with the prospective PhD supervisors as well as
selected specialist lectures. Students are required
to pass the MRes degree course before being
eligible to proceed to the PhD. Progression to the
PhD is expected but not automatic. Students are
then expected to complete their PhD research and
to submit their theses within three years. If
applicants already have an MSc or MRes degree in
an optics-related discipline, they may be exempted
from the requirement to study for the MRes
degree in Photonics.
Funding for research studentships
Broadly, most of our PhD students are supported
either by a centrally allocated studentship from
our EPSRC Doctoral Training Account (DTA), by a
Research Council, DTI or EU project studentship
(associated with a specific research grant), by a
scholarship designed for overseas students
(usually from the student’s own government), by
industrial sponsorship or by private funding. Note
that self-funded and externally funded students
are also required to study for the MRes+PhD
degrees where appropriate and should budget
accordingly. More information on scholarships and
awards can be found on our website.
When to apply
MSc in Optics and Photonics
We recommend that interested applicants apply to
study for a PhD with us as early as possible in the
academic year because we receive many
applications from final year undergraduates or
MSc students aiming to start in the coming
October. We note, however, that opportunities
can arise throughout the year and encourage
potential applicants to contact us as soon as they
decide they are interested in joining us.
If you are interested in a research career in optics
and photonics and are not ready or interested in
studying for a PhD, you may also wish to apply for
a place on our MRes or MSc courses. The MSc in
Optics and Photonics provides an excellent training
for the optics and photonics industry and MSc
graduates may also go on to study for a PhD in
Optics and Photonics.
Opportunities for the coming year
All academic staff members of the Photonics
Group aim to recruit PhD students for the next
academic year. We normally award EPSRC DTA
studentships to start in October, although it is
sometimes possible to start earlier. Please see our
website for a list of specific PhD projects for which
we are now recruiting. If you are interested in an
area not covered by this list of possible projects,
please do talk to the appropriate academic
supervisor, who may be able to advise you of other
opportunities.
Eligibility for PhD research within the
Photonics Group
We welcome applications for PhD research from
students around the world. Applicants should
have, or be expecting, a First class honours degree,
or a good Upper-Second, in physics or engineering
and be strongly motivated to undertake
challenging, cutting-edge research in photonics.
We believe that our research students'
achievements are, and should be, competitive with
those of the best research universities in the
world. This implies a world-class level of
commitment and professionalism from our staff
and our students. We place significant emphasis
on teamwork and effective communication.
PHOTONICS GROUP OPEN DAY TIMETABLE
WEDNESDAY JANUARY 30TH, 2013
14.00 – 14.30 Introduction to MSc in Optics & Photonics/MRes in Photonics by Kenny Weir and Andrew Williamson
in Room 630, Blackett Laboratory
14.30 - 15.00 Introduction to studying for a PhD in Photonics, in Room 630, Blackett Laboratory
15.00 - 16.30 Laboratory tours
15.00 - 15.20 Theoretical Projects Talk by Martin McCall, in Room 613, Blackett Laboratory. Attendees to join lab
tours following talk
16.30 - 17.30 Drinks reception and chance to meet current PhD students and research staff in Room 630, Blackett
Laboratory
Photonics Group Research
Our broad research themes are fibre and laser optics, electromagnetic theory, imaging technology and applications
and biophotonics. Current fibre/laser projects include compact and high power fibre and solid-state laser technology,
including broadly tunable supercontinuum sources, ultrafast fibre lasers, amplifiers and nonlinear optics. Theoretical
projects include rigorous electromagnetic theory (FE, FDTD, volume integral methods) applied to imaging, optical
storage and polarisation studies, chiral media, Bragg structures and photonic crystals. Our imaging projects focus on
adaptive optics applied to astronomy, microscopy and ophthalmic imaging and optical molecular imaging, including
multidimensional fluorescence imaging implemented in microscopy, endoscopy and tomography systems, applied to
tissue diagnosis, molecular biology and drug discovery. Most of our projects are interdisciplinary and we work
closely with industry.
http://www3.imperial.ac.uk/photonics
Optical fibre laser technology
S.V. Popov and J.R. Taylor
Over the past year, the emphasis of the group’s research has redirected from high average power supercontinuum
sources towards short pulse, fibre-based, wavelength specific sources. Although all-fibre high average power
supercontinuum sources, as originally developed by the group, are commercially successful and finding diverse
applications, they are frequently spectrally filtered to provide radiation in only a single or a few wavelength bands.
Apart from being an inefficient means of generating such radiation, such sources provide limited (albeit relatively
impressive) average spectral power densities of a few tens of milliwatts per nanometre that constrain the range of
potential applications. It may be more efficient in many circumstances to employ MOPFA (master oscillator power
fibre amplifier) configurations, which are themselves the basis of many supercontinuum pump sources, to directly
provide the pump radiation for specific nonlinear optical processes as a means to achieve high (watts) average
powers at specific wavelengths. To this end we have investigated both parametric and Raman generation, both in
conventional and photonic crystal fibres, as potential means to high power spectrally versatile radiation.
For the first approach we have developed a parametric source synchronously pumped by a Yb based MOPFA at 1 m
in the long pulse picosecond regime and achieved fibre dependent phase matched generation to the red. For the
latter approach, we have developed passively mode locked Raman lasers utilizing both carbon nanotubes and
graphene as nonlinear (saturable) absorbers. Graphene provides a tuning range of operation from 400 nm to
2000 nm and, coupled with fibre based Raman gain, represents a route to a universal ultrashort pulse source that is
limited only by the wavelength of the pump laser. This pump can itself be a c.w. tunable fibre Raman laser - thus
allowing almost unlimited wavelength ultrashort short pulse coverage. Initial investigations have concentrated in the
mid infrared, employing normally dispersive cavities to produce long, linearly chirped picosecond pulses that can be
temporally compressed using anomalously dispersive fibres or grating pairs. Operation in the visible spectral region is
currently under investigation. One disadvantage of current carbon nanotubes and graphene absorbers is the
potential of optically damaging the polymer host in which they are held. We are currently investigating the
application of ionically doped glass hosts, which should provide absorbers that are less susceptible to absorptive
damage. We are also investigating quantum dots in glass as alternative saturable absorbers for fibre lasers.
For spectral coverage in the 1100 nm to 1500 nm range, we are
investigating Bismuth doped silica fibres to provide a
broadband gain medium, although it offers a relatively modest
efficiency compared to the more common rare earth active
ions. For optical telecommunications we have demonstrated
the first picosecond amplification at high bit rates (~20GBit/s),
indicating the potential of bismuth to provide much-needed
bandwidth extension.
For high power applications, we are also developing Tm-doped
fibre chirped pulse amplifier schemes at 2 m and large mode
area passively mode-locked femtosecond Yb fibre lasers with
proposed power scaling to the 30-50 W average power regime.
Second harmonic generation of Bi-doped fibre
laser at 589 nm
Fibre laser sources for medical applications
S. V. Popov
In collaboration with industrial integrators and the Department of Surgery at Imperial College London, Imperial NHS
Trust and the Department of Computing, we are developing and implementing trials of wavelength-specific laserbased devices for urological, Ear Nose Throat, and robotically assisted surgery.
Developing spectrally versatile all-fibre laser technology using doped, Raman or frequency doubled fibre lasers allows
us to build single or multiple wavelength fibre laser systems of tens of watts average power for therapeutic medical
applications. By adjusting the irradiation wavelength we can optimise the interaction with the tissue, maximizing the
tissue removal or coagulation while minimizing the surrounding thermally affected zones and hence potentially
reducing pain effects and rehabilitation time. Furthermore, optical fibre based instruments have the inherent
capability to deliver light to a desired location and to operate metal-free in magnetic field environment like MRI.
Bismuth based MOPFAs have also been developed and frequency doubled to generate tunable radiation in the 590
nm regime for skin pigmentation treatment and ophthalmic coagulation However, to be competitive it will be
essential to improve the efficiency of Bi based devices through studies of the photophysics of the active ions.
Spectral range of tissue chromophores with therapeutic laser wavelengths indicated (left), together with laser surgical
tools (top right) and compact fibre laser (bottom right)
Nonlinear Optics and Laser Technology
G. Thomas and M. Damzen
Lasers have had a profound impact on society by enabling
technologies in manufacturing, telecommunications, medical and
sensing applications to name a few. We are developing a range of
cutting-edge all-solid-state lasers and nonlinear optical
technologies that exploit novel basic science techniques but are
focused on solving next-generation technological problems
ranging from precision laser manufacturing (e.g. processing of
solar cells) to satellite-based remote sensing (e.g. Earth
Observation for weather prediction and climate change science).
A key feature of our research is the radical new diode-pumped
micro-slab laser technology pioneered in our laboratory,
demonstrating a unique combination of performance, including
World’s highest power diode-pumped
compact size, ultra-high efficiency, high power, excellent beam
Alexandrite Laser, with high pulse energy
quality and controlled pulse delivery. The micro-slab technology
(>23mJ @ 100Hz) developed as a source for
has been commercialized through spin-out company Midaz Lasers
next generation satellite-based remote sensing.
Ltd, founded by Prof. Damzen in 2006, which has engineered and
delivered lasers and amplifiers world-wide to enable next generation manufacturing. It forms a collaborative link
between our basic research work and the route to commercial markets where appropriate. In collaboration with
Midaz, we have recently developed the world’s highest power diode-pumped Alexandrite laser. We have developed
this highly efficient, broadly tunable laser for the European Space Agency (ESA) for next-generation satellite-based
remote sensing, but it also has potential as an amplifier technology for high energy femtosecond lasers for cuttingedge light-matter interaction science. Our group is also a world-leader in self-organising lasers that can “intelligently”
self-correct their operation by exploit dynamic (nonlinear optical) holography inside the laser. We have recently
demonstrated how multiple self-organising lasers can be made to “communicate” and organise themselves into a
single coherent “super-mode” laser output, as a route to high power scaling of lasers.
Space-time Cloaking
A. Favaro, P. Kinsler, M. McCall
We have extended the idea of cloaking
objects in space to hiding events in
space-time. Whereas a spatial
electromagnetic cloak is designed to
caress light around an object as shown
in figure (a), rendering it invisible to a
distant observer, in the new scheme one
spatial variable is replaced by time.
Instead of deviating light rays around an
object, different portions of a ray are
sped up and slowed down such that
certain events are never illuminated, as
represented in figure (b). On reversing
the process, the illuminating light is
restored to its original uniform condition
so that a distant observer will never
Representations of (a) spatial cloak and (b) space-time cloak in which
the which the object is never illuminated by the evolving light
distribution such that the observer sees an “undisturbed” uniform light
sheet
suspect the occurrence of the un-illuminated events.
The design arose from manipulating the covariant form of Maxwell's equations under coordinate deformations,
which, for the event cloak, must embrace time as well as space. Reinterpreting such deformations as a dynamic
change of material parameters, a hole in space-time can be actualised in a physical medium. The best event cloak
solution turned out to be a design in which the material is engineered to appear as though it is moving. When this
effective speed varies for different points on the ray, as well as varying with time, the prescribed light-speed
modulation can be achieved. Although such a design is beyond current metamaterials technology, we proposed a
simple event cloak using programmable nonlinearity in optical fibers and recently the first such experimental spacetime cloak has just been demonstrated in the laboratory at Cornell University. The “event cloak” concept has opened
up a significant new cloaking paradigm that is only just beginning to be explored. It was hailed by a panel of
journalists as the third most significant breakthrough in Physics for 2011, and was selected for feature in the OSA’s
‘Highlights’ for 2011.
Electromagnetic Imaging with Applications to Sensing and Microscopy
C.A. Macias Romero, M.R. Foreman, P. Török
Our research is centred on applications of high numerical aperture,
electromagnetic imaging. A key strength is ultra high-resolution
micropolarimetry, with which it is possible to determine the
polarisation properties of samples such as 2-D and 3D metamaterials
and micromagnetic structures with extreme accuracy. The example in
the figure shows the measured polarisation map of the diattenuation
exhibited by a silver nanowire when illuminated with 405 nm
radiation. A more prosaic application of micropolarimetry is optical
data storage where we aim to increase the maximum information
content per unit area on an optical disk using an approach we describe
as Multiplexed Optical Data Storage (MODS) that encodes more than a
single bit of information into a single pit. We are also exploring the
optical nonlinearity of materials with a view to increasing the numerical
aperture of the lens.
Polarisation map of the diattenuation
exhibited by a silver nanowire
A significant new research effort is focused on sensing and detection of bacteria at low concentration in their natural
environment. We have developed a solution for detecting bacteria in the order of minutes without the need for
incubation. We are also working in collaboration with the Institute of Food Research to study pathogenic bacteria by
means of localisation microscopy and dielectrophoretic trapping. With C. Paterson we are developing confocal
Brillouin scattering microscopy to measure the 3-D micromechanical properties of bacteria and biofilms, as well as
polymers where time dependent polymerisation can be mapped.
Programmable Light
M. Neil
We are working to manipulate light in a programmable fashion for applications in
microscopy, metrology and the life sciences. We continue to develop the application
of spatial light modulators, using this technology to define arbitrary wave-front
shapes for metrology of large mirrors, to control the point spread function in
microscope systems for polarisation and super-resolution imaging and for optical
trapping. As part of the Single Cell Proteomics project at Imperial, we are using
optically trapped and biochemically functionalised oil droplets - Smart Droplet
Programmable interferometer
map of a mirror substrate
Microtools - to manipulate and probe biological cells. Research in this
area has recently been extended with EPSRC grants looking at protein
oxidation (the “Proxomics” project) nano-fluidics and fabrication (the
“Optonanofluidics” project) within the newly established Institute of
Chemical Biology at Imperial.
We continue to develop bio-imaging applications exploiting
Smart Droplet manipulated with optical
programmable light. We have recently started a collaborative EU
tweezer to trypsinize cell
funded project “OptoNeuro” using micro-led array technology for
opto-genetics, for which we are developing micro- and macro-optics systems to project light onto both cell cultures
and into the eye for prosthetic sight applications. In conjunction with Aurox Ltd we are working on structured
illumination projection systems for wide-field optical sectioning microscopy.
Multidimensional fluorescence imaging across the scales
Y. Alexandrov, S. Coda, G. Kennedy, S. Kumar, M. Lenz, A.
Margineanu, I. Munro, R. Patalay, C. Talbot, C. Dunsby, J. McGinty,
M. Neil, P. French
Our overarching mission is to create new opportunities for scientific
discoveries, particularly in biomedicine, by developing and applying
ultrafast and tunable laser and photonics technology to novel
imaging and metrology applications. We mainly work in
multidisciplinary collaborations with bioengineering, biology,
chemistry, medicine and physics, developing and applying
multidimensional fluorescence imaging (MDFI) technology, with a
particular emphasis on fluorescence lifetime imaging (FLIM), for
clinical diagnosis, molecular biology and drug discovery. Our FLIM
technology provides molecular contrast of different chemical species
and different fluorophore environments utilizing both one and two
photon excitation and implemented in instruments ranging from
multidimensional fluorometers for in vitro solution-based
measurements to super-resolved microscopy, high speed and
automated imaging of live cells, tomographic imaging in live disease
models and in vivo measurements in patients for clinical diagnosis.
3-D STED image of cortical actin and FLIM
STED of actin & Arp protein at
immunological synapse between cells
A key strength is our high-speed wide-field time-gated FLIM
technology that is being applied to clinical endoscopy and multiwell
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microscopy of cell biology, disease states in tissue and reactions in
microfluidic devices. Where appropriate, we combine optical sectioning and FLIM with multispectral or
hyperspectral imaging (realizing 5-D fluorescence imaging) or with polarization resolution to image rotational
diffusion dynamics. The latter may be used to obtain 3-D images of ligand binding or viscosity distributions.
We have recently developed a super-resolution FLIM microscope system based on STimulated Emission Depletion
(STED) microscopy, which allows sub-diffraction limited multilabel images to be obtained in a scanning confocal
microscope. As well as studying disease mechanisms in cell biology, we are also applying STED microscopy to study
nitrogen defects in diamond. To study cell signalling processes we apply FLIM and MDFI techniques to image protein
interactions using FRET, including in automated multiwell plate readers, and recently demonstrated multiplexed
FRET – simultaneously reading out two different protein interactions.
For drug discovery and for biological research, there is an increasing trend to translate live cell imaging experiments
and assays from monolayers of cells in culture to more physiological realistic contexts, including live disease models.
To this end we have developed the first FLIM-optical projection tomography system, which we have demonstrated
for imaging live disease models such as zebrafish. We have also developed a novel high speed 3D fluorescence
imaging system called Oblique Plane Microscopy (OPM) enabling dynamic events to be studied in 3D at video rate.
We also believe there is significant scope for translating our
imaging capabilities to clinical application for improved diagnosis,
intervention and drug discovery. For clinical studies we have
deployed a novel multiphoton microscope at Hammersmith
Hospital to exploit label-free autofluorescence contrast in tissue for
diagnosis of skin cancer, of which an example recorded in vivo is
shown in the figure. We are also developing FLIM endoscopes
utilising both wide-field time-gated imaging and laser scanning
microconfocal endoscopes. We have recently started our first in
vivo trial of a fibre-optic probe based multidimensional
fluorescence spectroscopy system for use in the gastrointestinal
tract and are developing novel illumination strategies for clinical
endoscopy and surgical procedures including a new approach to
laser scanning endoscopy that provides unprecedented
miniaturisation with no distal moving parts.
Clinical multiphoton FLIM microscope
with optically section FLIM image
Adaptive Optics and Retinal Imaging
D. Lara, C. Paterson
Adaptive optics initially arose to solve the problem facing
astronomers of how to overcome the severe limitation on imaging
resolution caused by the effects of random, dynamic aberrations
arising from atmospheric turbulence. In our research we are
developing the technology and applying it to other situations such as
biomedical microscopy and ophthalmic imaging. In the case of retinal
imaging, aberrations include dynamic contributions from the tear-film
dynamics as well as the aberrations from the cornea and lens.
Correcting aberrations using adaptive optics makes it possible to
image individual photoreceptors at the fovea and to obtain detailed
images of the cardiovascular system at the front of the retina. . The
Confocal scanning laser ophthalmoscope
principle is the same as for astronomy: the dynamic aberrated
image of the photoreceptor mosaic of the
wavefronts are measured using a wavefront sensor and corrected in
human retina
real time using an active deformable mirror. We are applying
information theoretical approaches to improve the efficiency of
wavefront sensing for this and other applications. We have also been applying estimation techniques from adaptive
optics to the analysis of retinal images which in collaboration with ophthalmologists at City are helping in the early
diagnosis of retinal diseases.
We are now extending our high resolution retinal imaging to include full polarisation properties of the retina, using
Mueller matrix imaging. This will enable us to image structures not possible with conventional techniques with the
hope that this will lead to new understanding of the causes of loss of vision where current treatments are ineffective.