Design of plasmonic nanostructures for an enhanced control over their ultrafast nonlinear optical response.

Lead Research Organisation: King's College London
Department Name: Physics


After a decade of existence, and driven by a remarkable expansion in research and development, plasmonics -the technology that exploit the unique optical properties of metallic nanostructures to enable routing and actively manipulating light at the nanoscale- has entered a defining period in which researchers will seek to answer a critical question: can plasmonics provide a viable technological platform which includes both passive and active nanodevices?
The design of these devices is driven by a two-fold objective: 1) to manipulate electromagnetic energy at the nanoscale, including harvesting, guiding and transferring energy, with high lateral confinement down to a few tens of nanometers, and 2) to generate ultrafast (a few femtoseconds) and strong non-linear effects with low operating powers to produce basic active functions such as transistor or lasing actions. Utilizing the resonant properties -field enhancement and spectral sensitivity- of Surface Plasmons Polaritons (SPPs) is generally thought to represent a practical avenue to achieving this objective.
However, our ability to control and manipulate light at this scale dynamically -i.e. to produce active functionalities- and in real-time through low-energy external control signals is a missing link in our aim to develop a fully integrated sub-wavelength optical platform. To date, active plasmonic systems, including thermo- and electro-optic media, quantum dots, and photochromic molecules, are achieving sensitive progress in switching and modulation applications. However, high switching times (>nanosecond) or the need for relatively strong control energy (~microJ/cm^2) to observe sensible signal modulation (35% to 80%), limit the practical use of such structures as signal processing or other active opto-electronic nanodevices.
In this context, this research aims to assess the potential for defects to enhance the non-linear optical properties of hybrid plasmonic crystals. The objective is to integrate defects, made of plasmonic cavities, in plasmonic crystals to create a focal point for electromagnetic energy stored in surface plasmon waves at the crystal's interfaces. The role of the defect is then to transfer this energy to a neighbouring non-linear material in order to change its optical properties at the femtosecond timescale, thus creating an active functionality. This research, largely based on ultrafast time-resolved near-field optical microscopy, is also expected to enhance our understanding of ultrafast energy transfers at the nanoscale- a critical expertise in designing nanodevices.

Planned Impact

Energy, health, and education are unarguably areas that need immediate attention with strong commitment in research, development, and training in order to build a sustainable society. These are the main areas this work aims to impact. This will occur directly or through selected intermediaries such as the information and technology industry. In particular, the Physics Department at King's has a strong ongoing partnership with several major players in this industry including INTEL, Seagate, Ericsson, Oxonica, and IMEC, with whom exchange and transfer of scientific and technical expertise take place on a continuous basis. How will this industry benefit from this work is a consequence of the crucial stage this industry has recently entered where the integration of optical devices (fast but bulky) and electronic devices (slow but highly integrable) would provide a giant leap in the performance of opto-electronic devices. These hybrid nanodevices are to be fast, strongly integrated, and not least, energy efficient. The research proposed here should therefore provide valuable knowledge for progress toward developing this new technology in terms of systems studied -plasmonic systems will play a pivotal role on the development of nanometer scale devices- and in terms of characterization technique that is resolved temporally, spatially, and energetically. In particular, enhancing the non-linear optical properties of plasmonic systems will provide grounds for the development of low-power consumption lasers and modulators, as well as ultra-sensitive detectors-all of which are integral components of an ultra-integrated circuitry platform. Understanding energy flow at the nanoscale will also allow us to improve the efficiency of solar cells and ultimately help design artificial systems that will overcome the theoretical efficiency limitations dictated by currently used materials such as silicon, to name but one. The potential benefits in terms of energy self-sufficiency and subsequent environmental impact are therefore immense. The health care industry will be a natural beneficiary from this research as well. Nanotechnology is increasingly applied to medical care (~30,000 patents in the last decade) from the development of diagnostic devices to the treatment of patients. However, applications are often constrained by bio-compatibility, lack of targeted (where is the treatment needed and what is it reacting with) treatment, and our finite knowledge of the complex nanoscale machinery of the human body limits the extend to which nanotechnology impacts this field today. Here again, our understanding of the driving forces governing the inner-workings of nanoscale systems and how these systems interact and exchange energy with their environment is central to the development of bio-compatible devices, will offer the capabilities to manufacture efficient and targeted diagnostics test and treatments, leading to better decease prevention and decreased hospital stays. On the educational front, the constant decline in interest for science witnessed in UK classrooms over the past decade is amongst the factors threatening the competitiveness of this country on the world stage. This has a direct impact on the quality of the research carried out and the innovative output of this research, whether in academia or in industry. This is particularly evident when comparing the EU's patent output -the UK situation is not an artefact- with the USA's and increasingly Asian countries. In this context, the proposed research will positively impact UK's competitiveness by implementing an original and state-of-the-art research program in nanosciences at King's. This will directly benefit KCL's students in their training but with the proper outreach strategy, should also be beneficial to the broader public and help attract, train and advise the next generations of scientists and engineers -a crucial element for UK's increased and sustained competitiveness.
Description We have discovered the ability for plasmonic crystals (the equivalent of photonic crystals but for surface plasmon polaritons) to demonstrate unusually strong nonlinear optical properties as a result of the introduction of defects in the crystal. This is a requirement for the design of active optical functionalities based on low-powered nonlinear processes. By engineering metasurfaces based on split-disk resonators, we have demonstrated a very strong second- and third-harmonic generation which can be controlled by external control light. Metasurfaces have been shown as a powerful platform for engineering of nonlinear optical properties.
Exploitation Route The problems addressed within this project have both scientific and potential economic impacts. From the economic standpoint, 2 patents have been filed and procedures are in place at King's to find suitable commercial outcomes for these inventions. At the academic level, the science underlying this work is being disseminated through the conventional routes (peer-review literature and conferences). Additionally, some of the output from this research is being presented to outreach events in the UK.
Sectors Energy,Other

Description The work performed in the project has lead to the discovery and development of integrated optical functionalities resulting in intellectual property. Two patents have been filed this year and ongoing efforts, with the support of dedicated KCL staff, are on finding commercialisation pathways.
First Year Of Impact 2014
Description ERC Advanced Grant
Amount € 2,737,327 (EUR)
Organisation European Union 
Sector Public
Country European Union (EU)
Start 09/2018 
End 08/2023
Description International Exchanges 2017 Round 2
Amount £11,995 (GBP)
Funding ID International Exchanges 2017 Round 2 
Organisation The Royal Society 
Sector Charity/Non Profit
Country United Kingdom
Start 12/2017 
End 12/2019
Description US ARO
Amount $600,000 (USD)
Organisation US Army 
Sector Public
Country United States
Start 05/2016 
End 04/2019
Description US Army Research Office
Amount $35,000 (USD)
Organisation US Army 
Sector Public
Country United States
Start 08/2013 
End 12/2013
Description studentship
Amount £140,000 (GBP)
Organisation Defence Science & Technology Laboratory (DSTL) 
Sector Public
Country United Kingdom
Start 09/2015 
End 08/2019
Description Argonne 
Organisation Argonne National Laboratory
Country United States 
Sector Public 
PI Contribution Investigation on nonlinear and ultrafast response of plasmonic nanostructures
Collaborator Contribution User access to the ultrafast spectroscopy facilities
Impact Publications, conference papers, exchange visits, internal ANL collaborative grants
Start Year 2010
Description UTT 
Organisation University of Technology of Troyes
Country France 
Sector Academic/University 
PI Contribution Investigation of optical and nonlinear optical properties of Al plasmonic crystals
Collaborator Contribution Fabrication of the samples of plasmonic crystals based on Al metal for harmonic generation in UV spectral range.
Impact Several joint papers have published and in preparation.
Start Year 2015
Title Cavity structure for plasmonic signal modulation and switching 
Description A plasmonic switching device and method of providing a plasmonic switching device. 5 The device comprises: a resonant cavity formed between surfaces, one of said surfaces comprising a plasmonic system operable to support at least one plasmonic mode; an electromagnetic radiation feed arranged to couple electromagnetic radiation into the resonant cavity and the at least one plasmonic mode. The resonant cavity is arranged to be switchable between: a first state in which the resonant cavity has an operational 10 characteristic selected to allow resonance of the electromagnetic radiation at a frequency of the at least one plasmonic mode such that excitation of the at least one plasmonic mode is inhibited in the plasmonic system; and a second state in which the operational characteristic of the resonant cavity is adjusted to inhibit resonance of the electromagnetic radiation at a frequency of said at least one plasmonic mode such that 15 said at least one plasmonic mode is excited in said plasmonic system. The cavity structure of aspects and embodiments described herein can offer high extinction ratios, together with reduced dimensions when compared to similar systems. The structures of aspects and embodiments described herein can be tailored for integration with VCSELs, which offer an efficient platform for SPP excitation, allowing the realisation of, 20 for example, an on-chip, plasmonic switch. 
IP Reference GB1400393.3 
Protection Patent application published
Year Protection Granted 2014
Licensed No
Impact none yet
Title Integrated photonic metamaterials for optical functionalities 
Description An electromagnetic waveguide transmission modulation device and method of providing such a device. The device comprises: at least one hyperbolic metamaterial element coupleable to the waveguide. The hyperbolic metamaterial element is arranged to be adjustable between: a first mode in which the metamaterial element is configured to support a resonant mode matched to a propagation vector of a 10 propagation mode supported by the waveguide such that propagation of a mode along the waveguide is affected; and a second mode in which the metamaterial element is configured to inhibit support of the resonant mode matched to the propagation vector, such that interruption of propagation of a propagation vector along the waveguide is prevented. The first aspect recognises that a device can be directly integrated with 15 waveguide, for example, silicon waveguide, technology. If integrated, a device in accordance with aspects and embodiments may provide a smaller device footprint, increase possible operating frequency and bandwidth and reduce power consumption when compared with alternative approaches. 
IP Reference GB1400398.2 
Protection Patent application published
Year Protection Granted 2014
Licensed No
Impact none yet.
Description Cleo Europe 2015: Munich 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Ultrafast Kerr nonlinearities in multimodal plasmonic metamaterials:elliptic, hyperbolic and epsilon-near zero regimes
S. Peruch, A. Neira, G. Wurtz, and A. Zayats;

Ultrafast All-Optical Switching of Surface Plasmon Polariton Modes via Fano Resonances C. McPolin, N. Olivier, J.-S. Bouillard
D. O'Connor A. Krasavin1, W. Dickson
G. Wurtz1, and A. Zayats

Bulk plasmon-polaritons in hyperbolic nanorod metamaterial waveguides
N. Vasilantonakis, M. Nasir, W. Dickson, G.A. Wurtz, and A.V. Zayats;
Year(s) Of Engagement Activity 2015
Description IOP lectures 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact The talk lead to discussions on the subject of optics, nano science and nanotechnology.

Several students came to London to visit the lab. Potential internships were discussed for the future.
Year(s) Of Engagement Activity 2012,2013
Description Nanophotonics and Related Techniques Conference (NFO12) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact "Design of a nanorod metamaterial for enhanced fast nonlinearities," A. Neira, G. Wurtz, P. Ginzburg, W. Dickson, N. Mazhar, A. V. Zayats, talk at the 12th Near-field Optics, Nanophotonics and Related Techniques Conference (NFO12), San Sebastian (Spain), 2012.
Year(s) Of Engagement Activity 2012
Description SPIE Optics and Photonics, San Diego 2015 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Transverse spin of surface plasmon polaritons and spin-orbit coupling effects in light scattering by plasmonic nanostructures, F. J. Rodriguez Fortuno, D. O'Connor, P. Ginzburg, G. A. Wurtz, A. V. Zayats, keynote talk at the Plasmonics conference,

Light emission in nonlocal plasmonic metamaterials, V. A. Podolskiy, B. Wells, P. Ginzburg, A. V. Zayats, invited talk at the Metamaterials conference, SPIE Optics and Photonics congress

Nonlinearities in hyperbolic plasmonic metamaterials, A. Neira, S. Peruh, G. Marini, M. Nasir, A. V. Krasavin, N. Olivier, W. Dickson, G. A. Wurtz, A. V. Zayats, invited talk at the Metamaterials conference,
Year(s) Of Engagement Activity 2015