School information

An EUPROMETA Doctoral School will be held right after the Conference (15 - 16 September 2023) in the same venue. The topic of the school will be

Electromagnetic Metamaterials for Energy Applications

The school aims to highlight the potential of electromagnetic metamaterials (and photonic structures in general) to face the global and long term challenge for green and sustainable energy solutions and technologies. School topics will include metamaterials for RF energy harvesting and wireless power transfer, metamaterials/metasurfaces for energy efficient wireless communications, photonic systems/materials for enhanced photovoltaic efficiency, metamaterials for radiative cooling applications, metamaterials/plasmonics for enhanced photocatalysis, metamaterials for thermal radiation management etc.

The school will offer a unique opportunity to students and young researchers (a) to know and understand the potential of photonic metamaterials to enable or advance green, efficient and sustainable energy technologies, (b) to meet pioneers and leading experts in this cutting edge and of high societal and economical impact research field, and (c) to get exposure to the latest developments in the field. Comprehensive lectures will take into account the widespread backgrounds of the audience.

Confirmed invited speakers (alphabetically):

Harry Atwater, California Institute of Technology, USA. Talk title: Tunable Metasurfaces: Control of Absorption, Emission and Scattering

Femius Koenderink, AMOLF, The Netherlands. Talk title: Metasurfaces for controlling and advancing light emission

Wei Li, Chinese Academy of Sciences, China. Talk title: Nanophotonics controlled thermal radiation and radiative cooling applications

Georgia Papadakis, ICFO, Spain. Talk title: Thermal photonics for energy

Thomas Pattard, American Physical Society. Talk title: Preparing publications for Physical Review Journals

Albert Polman, AMOLF, The Nederlands. Talk title: Optical metasurfaces for improved photovoltaics

Ekaterina Shamonina, Oxford University, UK. Talk title: Metamaterials for wireless power transfer

Sergei Tretyakov, Aalto University, Finland. Talk title: Metasurfaces for energy-efficient wireless communication systems

Rachel Won, International Editor, Nature Photonics.

Anatoly Zayats, King’s College, London, UK. Talk title: Plasmonic materials and metamaterials for photochemistry and sustainability

Jiafeng Zhou, University of Liverpool, UK. Talk title: Metamaterials for energy harvesting from Radio Waves

Lecture abstracts:

Harry A. Atwater: Electro-optically tunable active metasurfaces that enable dynamic modulation of reflection amplitude, phase, and polarization using resonantly excited materials and phenomena are powerful design elements for meta-imaging and computation.  As flat, low-profile optical elements, active metasurfaces have potential serve as cascadable, programmable components in optical meta-imaging systems, such as lens-less cameras and single-photon imaging systems.  Active metasurfaces that enable dynamic complex index modulation to vary the amplitude, phase and polarization have been recently explored using several active materials and modulation phenomena, including carrier index in plasmonic ENZ structures, reorientation of liquid crystal molecules, electrooptic effects in quantum well heterostructures and polar perovskite materials, as well as index changes in phase change materials.   Recently also, metasurfaces that employ dielectric phase-gradient elements with high quality factor non-local as well as local resonances have expanded the design space for active metasurfaces by enabling silicon and other more conventional  dielectric materials with modest values of index change to be utilized. We can develop a taxonomy for active metasurfaces based on the attainable degree of spatial and temporal control. The spatial phase gradient arising from phase-reconfigurable array elements can enable continuous phase gradient tuning for beam steering or varifocal lensing. The degree of temporal control is connected to the reconfiguration timescale: In quasistatic metasurfaces, temporal gradients are slow compared to the period of electromagnetic waves, while time-modulated structures feature temporal gradients modulated fast enough to alter the frequency of the scattered beam. This opens the possibility to frequency multiplex scattered beams from active metasurfaces to facilitate harmonic beam steering in which a single active aperture steers scattered beams for different frequencies at independent angles.

In this talk, I will discuss metasurfaces with high quality factor, local, resonant elements capable of two-dimensional phase gradient generation, in both passive and active metasurface designs.  I will also describe active metasurfaces with both spatial and temporal phase gradients, and an active metasurface as a lens-less imaging system, and compare the characteristics to conventional lens-coupled image sensors.

Wei Li: I will discuss how one can use nanophotonic structures to control thermal radiation and radiative cooling, as well as novel applications of radiative cooling in thermal management and energy harvesting.

Georgia Papadakis: In this talk, we will cover basic concepts in thermal radiation control. We will start with the notion of thermal emissivity, and describe ways to tailor and probe it experimentally. Based on this, we will learn how the emissivity of a thermal emitter affects the energy conversion efficiency of light-based radiative heat engines, such as solar photovoltaic systems and thermophotovoltaic systems. We will also discuss ways to leverage properties of emerging materials for precise directional control of thermal emission. We will then transition to the thermal near-field, where more exotic effects take place, leading to super-Planckian thermal emission and its implications in the efficiency of radiative heat engines. Based on a simple analytical theory for near-field heat transfer, we will classify various relevant materials in terms of their performance as thermal emitters.

Albert Polman: The lecture will start with a perspective on the build up of photovoltaics industry in Europe, to gain strategic independence and profit from the enormous economic benefits that the energy transition offers us all in Europe, based on a recent plan that we have developed (www.solarnl.eu).  I will then introduce the scientific challenges that must be overcome, I will introduce the use of light scattering plasmonic and dielectric metasurfaces to enhance light coupling and trapping in photovoltaics. I will present an integrated near-field/far-field scattering matrix formalism for light trapping in silicon and multifunction solar cells enhancing photo current. I will discuss how metallodielectric nanostructures can help create spatially selective carrier generation profiles, enhancing photovoltage. Plasmonic and cloaking nanostructures to create transparent conducting contact layers will also be discussed.

Sergei Tretyakov: The power transfer efficiency of existing wireless links in telecommunication systems is ridiculously low. In a typical scenario of a wireless link between a base station (at the frequency of 3 GHz, as a typical example) and a mobile phone (say, at 2 km distance) only about 0.00000001 % of the energy radiated by the base station antenna carries the signal to the mobile phone. The remaining 99.99999999 % heats the environment and causes interference to other devices. A feasible way to increase power efficiency is increasing antenna gain (working at high frequencies) and shaping the propagation channel using metasurfaces. In this lecture, I will present some examples of design and testing of energy efficient reconfigurable and fixed metasurfaces for future mobile communication networks.

Anatoly Zayats: The coherent oscillations of mobile charge carriers near the surface of good conductors -- surface plasmons -- are being exploited in many applications in information technologies, clean energy, high-density data storage, photovoltaics, chemistry, biology, medicine and security. Light can be coupled to surface plasmons and trapped near the interface between a metal and an adjacent material. This leads to the nanoscale confinement of light, impossible by any other means, and a related electromagnetic field enhancement. Microscopic electron dynamic effects associated with surface plasmons are capable of significantly influencing physical and chemical processes near a conductor surface, not only as a result of the high electric fields, but also via the excitation of energetic charge carriers: holes below Fermi level or electrons above it. When remaining inside plasmonic media, these so-called hot carriers result in nonlinear, Kerr-type, optical effects important for controlling light with light. They can also transfer into the surroundings of the nanostructures, resulting in photocurrent, or they can interact with adjacent molecules and materials, leading to photochemical transformations, which sometime difficult to achieve otherwise. In this series of lectures, we will discuss:

• Dynamics of hot-carrier excitations in plasmonic materials;
• Metamaterials, metasurfaces and metaparticles for engineering the required light absorption and hot carrier generation;
• Applications of plasmonic hetero-nanostructures and metamaterials in photochemical transformations;
• Reactive plasmonic tunnel junctions and related effects.

Jiafeng Zhou: This talk will explore the potential of using metamaterials and metasurfaces to improve the efficiency of wireless energy harvesting systems. By reducing the sensitivity of reception to incident wave angles and polarizations, these materials have the ability to significantly enhance energy conversion. The discussion will cover the design considerations and techniques for incorporating metamaterials into energy harvesting systems, as well as the potential opportunities for future development.