Riddle time!

In need of a break? Try this for a bit of a change:

6 4 2 7
4 2 0 5
8 4 X 6
8 6 4 8

Can you figure out what to replace the X with?

Too easy? Got another one? Please email your riddle suggestions to

The solution to last newsletter’s riddle: 64.

Training and other events in April 2018

Please see below a schedule of what is happening in April 2018 – and what had to be cancelled due to unforeseen circumstances.

The cancelled meetings for the CDT cohorts and the Programme Manager will be rescheduled in due course.

Date Training/Event Cohort Time Venue
04.04.2018 CDT Group Meeting Group 2 13.30 – 14.30 Har 209
05.04.2018 Student Feedback Meeting


4th Years 10.00 – 11.00 Phy SCR
11.04.2018 Student Feedback Meeting


2rd Years 10.00 – 11.00 Phy SCR
11.04.2018 CDT Group Meeting Group 3 13.30 – 14.30 Phy 124
12. 04.2018 Student Feedback Meeting


3nd Years 10.00 – 11.00 Phy SCR
18.04.2018 CDT Group Meeting Group 4 13.30 – 14.30 Phy 124
19.04.2018 Student Feedback Meeting 1st Years 10.00 – 11.00 Phy SCR
24.04.2018 Physics Theory Seminar: Pieter Kok, Sheffield University.  Title tbc All 13.30 – 14.30 tbc
25.04.2018 CDT Group Meeting Group 1 13.30 – 14.30 Har 209
27.04.2018 6 Month Project Viva to be completed and feedback submitted 1st Years

New Publication: Plasmon polaritons in cubic lattices of spherical metallic nanoparticles

Charlie-Ray Mann published an article on Plasmon polaritons in cubic lattices of spherical metallic nanoparticles in Physical Review B.   In addition, Charlie informed us that his next publication has just been accepted by Nature Comms. We look forward to posting the link to it as soon as it becomes available online. Congratulations, Charlie, well done!


We theoretically investigate plasmon polaritons in cubic lattices of spherical metallic nanoparticles. The nanoparticles, each supporting triply-degenerate localized surface plasmons, couple through the Coulomb dipole-dipole interaction, giving rise to collective plasmons that extend over the whole metamaterial. The latter hybridize with photons forming plasmon polaritons, which are the hybrid light-matter eigenmodes of the system. We derive general analytical expressions to evaluate both plasmon and plasmon-polariton dispersions and the corresponding eigenstates. These are obtained within a Hamiltonian formalism, which takes into account retardation effects in the dipolar interaction between the nanoparticles and considers the dielectric properties of the nanoparticles as well as their surrounding. Within this model we predict polaritonic splittings in the near-infrared to the visible range of the electromagnetic spectrum that depend on polarization, lattice symmetry, and wave-vector direction. Finally, we show that the predictions of our model are in excellent quantitative agreement with conventional finite-difference frequency-domain simulations, but with the advantages of analytical insight and significantly reduced computational cost.

Figure (a),(b): Density plots for the distribution of the electric field of the low-energy transverse polaritonic modes, shown on a plane cutting through the center of the primitive cell. These distributions are calculated at q=0.49π(ˆx+ˆy)/a in the direction of the twofold symmetry axis, using the parameters rnp=10nm, a=3rnp, εd=5.6, εm=1, ωp=9.6eV/ℏ, and γD=22.8meV/ℏ [47]. The dipolar modes exhibit a polarization oriented in the (a) ˆy−ˆx and (b) ˆz directions.
>> See all XM2 publications on www.exeter.ac.uk/metamaterials/research/publications/ <<

XM2 thesis submission by Alba Paniagua Diaz: “Light in scattering media: active control and the exploration of intensity correlations”

It is our pleasure to announce that Alba Paniagua has recently submitted her PhD thesis on “Light in scattering media: active control and the exploration of intensity correlations” (abstract below), supervised by Jacopo Bertolotti and Bill Barnes.

Alba is a driven researcher with strong leadership qualities. For example, she represented her peers as member of the CDT Student Advisory Group in discussions with the Management and Oversight Boards (2016/17), and became the first female president of the international society for optics and photonics (SPIE) student chapter at Exeter (2015/16). During that time she built bridges between SPIE and the College’s Early Career Researcher Network to co-host a workshop on Careers in Optics for the benefit of all interested postgraduate and postdoctoral researchers.

Alba has presented her research at several national and international conferences, such as Optics & Photonics in San Diego (CA) or CLEO Europe in Munich, and is currently writing 3 research papers to publish the results of her PhD project.

She is planning to continue her research for 3 more months as a postdoc at Exeter, and is looking forward to taking some time in summer 2018 to identify her next steps and careers options. Alba’s home country Spain is close to her heart, and will hopefully be able to offer her good job opportunities in the future, but in the meantime she has set her mind on exploring the wider world within and outside the research community, e.g. in Australia or in the US, to widen her expertise and network.

A highlight of Alba’s PhD studies was the extended research stay at the Fraunhofer Center of Applied Photonics in Glasgow in 2017, where she worked with Dr David Stothard, Deputy Head of Department, Lasers and Laser Systems and his research team on building a ring cavity laser – an experience she highly values and recommends to any postgraduate researcher.

The CDT’s “Beyond A PhD” speakers were of particular inspiration to Alba, as the visiting speakers (e.g. Helen Thomas, BBC executive producer) helped her to understand that there is a myriad of careers pathways open to a doctoral graduate in Physics. “It was eye opening to learn how many opportunities one can have – in academia, industry and beyond – and that it’s not just black and white but full of unexpected turning points.

Alba used several opportunities to share her passion for research with the wider public, e.g. through experiments at the IOP Festival of Physics (2014), the Physics Open Days (2015 & 2016) and the Big Bang event (2016) at Exeter.  She particularly enjoyed working with groups of school children and the watching the fascination in their eyes when the magic of Physics unfolds in front of them.

We are incredibly proud of Alba and have no doubt that she will successfully pass the viva as her final step towards the PhD degree. Looking a few years ahead it will be our pleasure to welcome her back at Exeter as a “Beyond a PhD” speaker to inspire future generations by sharing her experiences after graduating from the CDT in Metamaterials.

 Abstract of Alba Paniagua’ s PhD thesis

Light in scattering media: active control and the exploration of intensity correlations

When light encounters scattering materials such as biological tissue, white paint or clouds, it gets randomly scattered in all directions, which traditionally has been seen as a barrier for imaging techniques (reducing their resolution) or sensing, due to the reduction of the penetration depth of light. However, in recent years it has been shown that scattering might not necessarily be an impediment, and that the knowledge of the properties of multiple scattering can be indeed useful for imaging, sensing and other applications.

In the first part of this thesis we study the implications of manipulating the light incident on a multiply scattering material. We experimentally show how by actively controlling the output light of a bad quality laser we manage to not only improve its beam quality, but also in an energy-efficient way, in comparison with traditional methods. In a different experiment presented in this thesis, we show how the active control of the light incident on a scattering material can be useful to improve sensing through scattering media, by means of increasing the transmission and energy deposited inside.

In the final part we present the first experimental observation of intensity correlations between transmitted and reflected patterns from a scattering material, exploring how it depends on the parameters of the scattering medium. In the last part of the thesis we present a new imaging technique based on the use of the intensity correlations described in the previous chapter, opening new possibilities to non-invasive imaging through highly scattering materials.


Figure: Increase of the penetration depth of light in scattering media by wavefront shaping techniques. a) Schematic of a plane wave illumination incident on a scattering material, where most of the light is reflected and only a small portion of it, transmitted. b) Schematic of light propagation through a scattering material when only the wavefront has been modified to increase transmission through the sample. c) Raman scattered light from the inner layer (blue) of the sample when the beam is non-optimized (red) and when it is optimized (green). It shows that the optimized wavefront is capable of delivering more than 40% extra intensity at deeper positions.

New Publication: Influence of luminescent graphene quantum dots on trypsin activity

Tanveer Tabish‘s paper Influence of luminescent graphene quantum dots on trypsin activity has been published in the International Journal of Nanomedicine:

Background: Protein–graphene interactions have the potential to play a pivotal role in the future directions of nanomedicine. These interactions lead to diverse processes such as generation of protein coronas, nano–bio interfaces, particle wrapping, and biocatalytic processes that could determine the ultimate fate of graphene nanocomposites in biologic systems. However, such interactions and their effects on the bioavailability of graphene have not yet been widely appreciated, despite the fact that this is the primary surface in contact with cells.
Methods: This paper reports on the integrative physiochemical interaction between trypsin and graphene quantum dots (GQDs) to determine their potential biologic identity in enzyme engineering. This interaction was measured by a wide range of analytical methods.
Results: Definitive binding and modulation of trypsin–GQDs was demonstrated for the first time by use of vibrational spectroscopy and wetting transparency, which revealed that trypsin was absorbed on GQDs’ surface through its cationic and hydrophilic residues. Our findings suggested that trypsin’s active sites were stabilized and protected by the GQDs, which were likely to be responsible for the high bioavailability of GQDs in enzymes.
Conclusion: Our work demonstrates the efficacy of GQDs as an enzyme modulator with high specificity, and their great application potential in enzyme engineering as well as enzyme-based therapies.

Congratulations to Tanveer and the Co-authors!

“And the best pitch award goes to …” – Angus Laurenson reports on his experiences at the SpaceTech Entrepreneur Programme

Our postgraduate researcher  Angus Laurenson returned recently from the 3 day SpaceTech Entreprenuers Programme (February 2018) at Exeter Science Park – with a lot of new knowledge about the space industry and start-up businesses in general. Funded by the UK Space Agency and delivered by the South West Centre of Excellence in Satellite Applications, SETsquared Exeter and Goonhilly Earth Station, SpaceTech is the perfect start-up accelerator  to create a product or business using satellite data and technology.

The event provided a platform for the UK space industry to report on latest developments and iniatives, with particular focus on the southwest (for example on the proposed spaceport at Newquay airport and Goonhilly earth station). Talks ranged from startup incubators explaining what funding and support is available for startups or other businesses to the UK space agency’s outlook as well as established players in the commercial space industry such as Thales Alenia, a large European satellite manufacturer, and Spirent, a local GPS calibration and testing company.

The majority of the programme was however dedicated to a hands-on team challenge: development of a spacetech business cases. Among the contestants was the Flann Microwave team consisting of James Watts, CEO of Flann Microwave; Oliver James, Flann Microwave; Angus Laurenson, PhD Student in the CDT for Metamaterials, University of Exeter; and Evie James, Undergraduate at Exeter Business school, Penryn.

Angus summarised the business case challenge his team set for itself: how to break into the space market where satellite manufacturers are extremely risk averse and are unwilling to take on a supplier who has not had their hardware flown into orbit yet.  To tackle this challenge they focussed on applying the “golden circles of business“,  the idea being that a company does not market its products, instead it should market its values to trigger an emotional response that resonates strongly with the customer.

The team’s strategy was to find ways to deploy Flann products into space, whilst at the same time leveraging the good reputation for reliability and quality that Flann enjoy with their existing customer base in order to spread that trust to new clients.

Angus learned a lot about market segmentation (who they were going to target specifically), pricing methods, estimating the size of the opportunity, development of the business finances (operating profit, gross revenues, costs etc), and the different sales models a business can operate.

A “3 minutes – 3 slides”  pitch of the participants’ business plans on problem / solution / opportunity concluded the day. Oliver James, a new recruit at Flann Microwave, presented on behalf of the Flann team how they were going to grow their business and turn a profit – and, rest assured, the team won the best pitch award.

Angus conclusion on the experience: “We won the best pitch award, which was the icing on the cake, and I would recommend those interested to attend the next rendition of this workshop.”


Exeter Acoustics Metamaterials Meeting: 16 & 17 April 2018

The first Exeter Acoustics Metamaterials (XAM3) Meeting will take place at the University of Exeter on Monday April 16th and Tuesday 17th April 2018. This two-day meeting will explore the latest developments in acoustic metamaterials/metasurfaces and industrial engagement with university research in the field.

It aims to bring together industrialists, established academics, and early career researchers from world-leading institutions to identify overlapping and complementary interests and to understand where specific expertise may be shared.

The event, which is free to attend, is funded by Exeter’s EPSRC Centre for Doctoral Training in Metamaterials, with further sponsorship from the EPSRC UK Acoustics Network. It will include presentations from invited speakers (academics and industry representatives), a poster session, and plenty of opportunities for discussion including a networking dinner on Monday 16th April.

To register please use the registration form.

If you have any further questions, please don’t hesitate to get in touch with the event organiser Dr Tim Starkey: T.A.Starkey@exeter.ac.uk.