Light in Complex Nanostructures

The Light in Complex Nanostructures (acronym COS) group studies the properties of coherent systems involving multiple and strong scattering of light with individual or ensemble of quantum or classical nano-objects or both. We tackle the problem starting from the elementary level (individual nanoresonators), to the microsystem level (nanoresonators possibly dressed by quantum emitters, small nanoresonator assemblies), towards the mesoscopic scale (metasurfaces).

OPEN POSITIONS

The group would be delighted to successfully support the application of a young researcher for a junior (Chargé de Recherche) CNRS position in January 2026.

The group received significant grants in 2023 & 2024 and is presently offering several postdoc positions:

Within the ERC Advanced project UNSEEN (2.2 M€), we study disordered metasurfaces to synthesize new visual effects. We try to understand how to design the structures to control their far field appearance attributes, such as specular and diffuse colors, glossiness, transparency, iridescence… More details on the topic can be found in Nature Mater. 21, 1035 (2022) and ACS Nano 17, 6362 (2023). Talented PhD students are also welcome.
In collaboration with ST-Microelectronics (Grenoble), we develop new numerical electromagnetic techniques and software for analysing large optical metasurfaces. The postdoctoral researcher will develop a freeware based on a method called global polarizability matrix (JOSA A 37,70-83 (2020)) and will validate the numerical simulations by comparing them with real experimental data collected by our partners at ST-Edinburgh.
For the ANR project WHEEL on Non-Hermitian physics and quasinormal modes, we study the properties of light in time-varying nanoresonators. For an illustrative example of our work, see our freeware published in Computer Physics Communications 284, 108627 in 2023.

CURRENT MEMBERS

Philippe LALANNE (CNRS Research Director, philippe.lalanne@institutoptique.fr, google scholar, middle)
Louis FORESTIER (ERC PhD, not on the picture, October 2024 - September 2027)
Miao CHEN (ERC Post-doctoral fellow, google scholar, leftmost, June 2022-24)
Thomas CHRISTOPOULOS (Marie Curie Post-doctoral fellow, not on the picture, google scholar, November 2024 - October 2026)
Tong WU (Post-doctoral fellow, google scholar, right, Mai 2024 - Dec. 2025)
Yuhao XU (ERC Post-doctoral fellow, not on the picture, March 2024 - Feb. 2027)
Minggang Luo (ERC Post-doctoral fellow, google scholar, rightmost, September 2024 - Feb. 2027)

ASSOCIATE MEMBERS

Loïc TRAN (PhD student, collaboration L'Oréal, Paris)

FREEWARES

The group has launched 4 freeware packages: MAN, RETOP,RETICOLO and RETICOLOfilm-stack. A 40min presentation of the packages and their utilities can be found on Youtube. The following graph shows the download statistics of the first three freewares since January 2020 (month 0).

MAN (Modal Analysis of Nanoresonators)

MAN is an open-source software developped in Matlab, designed to analyze electromagnetic resonators. It relies on two solvers, QNMEig and QNMPole, which compute and normalize the quasinormal modes (QNMs) of the resonators. QNMEig operates under the COMSOL Multiphysics platform; QNMPole can be used with any frequency-domain electromagnetic solver. These solvers are valued by an increasing number of toolboxes, which allow a transparent analysis of nanoresonators: field reconstruction in the modal basis, scattering cross-section spectra, LDOS maps, Purcell factor, multipolar decomposition, generation of second-harmonics, temporal domain analysis, Fano parameters (2025) …

Details on the freeware are found in Computer Physics Communications. See also the userguide video or the introduction video.

Download MAN from ZENODO

RETOP

RETOP is an open-source numerical tool developped in Matlab, designed to implement near-to-far-field transformations for light scattering or emission problems involving local inhomogeneities, such as scatterers, current sources, or combination of both, embedded within stratified media. Quite uniquely, RETOP computes in-plane radiation diagrams in guided and plasmonic modes.

To compute radiation diagrams, RETOP just needs to know the near-field computed on a rectangular box that contains the object. This computation can be performed with any full-wave Maxwell solver, including COMSOL. Special attention is made to the interface with COMSOL Multiphysics. In 2024, RETOP was integrated into COMSOL V6.2 (excluding the option related to guided modes).

Download RETOP from ZENODO

RETICOLO

RETICOLO implements the rigorous coupled wave analysis (RCWA) for 1D (classical and conical diffraction) and 2D crossed gratings. It operates under a MATLAB environment and incorporates an efficient and accurate toolbox for visualizing the electromagnetic field in the grating. As a spinoff, V9 and later versions incorporate a toolbox to analyze thin film stacks made of uniform media with arbitrary anisotropy.

Download RETICOLO from Zenodo

RETICOLOfilm-stack

RETICOLOfilm-stack is the latest freeware launched in 2024. It is written in MATLAB. It computes the reflection and transmission of arbitrary stacks of anisotropic thin films in a vectorialized manner for multi wavelengths and incidences. It further allows you to compute the modes, e.g. surface polaritons, waveguide modes, guides or leaky of the stack.

Download RETICOLOfilm-stack from Zenodo

RECENT TEXTBOOK PUBLICATIONS

The textbook Introduction to Nanophotonics (Oxford Univ. Press 2022) introduces major advances in the field of artificial metallic and dielectric nanostructures. The material is designed for graduate students with a background in physics and electrical engineering.

Introduction to Nanophotonics is more than a treatise on photons ans electrons being lost on tiny islands or in a jungle of nano-structured materials; the authors discuss numerous useful configurations while ensuring the reader does not lose sight of te underlying principles, includind an unprecedentedly clear description of the role of plasmons." Dieter Pohl, University of Basel

You can freely download a PDF version that closely resembles the published version.

ALUMNI

Roman Calpe (PhD student, Joensuu Univ.)
Benjamin ROUSSEAUX (Post-doctoral fellow, now Assistant Professor at Univ. Bourgogne Franche Comte)
Adrian AGREDA (Post-doctoral fellow, now at ELORPrint Tec)
Marie-Caroline SOLIGNAC (PhD student, collaboration SVI - Saint Gobain Recherche)
Denis ARRIVAULT (CNRS Research Engineer, now at INRIA-Bordeaux)
Maxime BERTRAND (PhD student, now at SharpEye, Paris)
Armel PITELET (Post-doctoral fellow)
Kevin VYNCK (CNRS Research Scientist, now at Institut Lumière Matière, Lyon, France)
Louis BELLANDO (Post-doctoral fellow, now at LOMA, Talence, France)
Kévin COGNEE (PhD student, now at City University of New York, USA)
Rémi FAGGIANI (PhD student, now at Greenerwave, Paris, France)
Alexandre GRAS (PhD student)
Wei YAN (Post-doctoral fellow, now at Westlake University, Hangzhou, China)
Jianji YANG (Post-doctoral fellow, now at Facebook, California, USA)
Xiaorun ZANG (PhD student, now at Tampere University of Technology, Finland)

BIOGRAPHY Philippe Lalanne

Philippe Lalanne is a CNRS Research Scientist and a leading expert in computational and nanoscale electrodynamics. His early work at Institut d’Optique in Orsay with Pierre Chavel focused on optoelectronic implementations of stochastic neural networks and simulated annealing. After a sabbatical in 1995 with G.M. Morris at the Institute of Optics in Rochester, he shifted his focus to diffractive optics. Since then, Lalanne and his colleagues have developed new numerical tools [Reticolo,CPC23] and modal theories to analyze nanostructured surfaces [JOSAA96], photonic-crystal waveguides [JOSAA01,OExpress07] and nanoresonators [LPR18,PRB18,OE22]. These advances have deepened the understanding of key nanoscale optical phenomena, such as light confinement in photonic-crystal cavities [Nature04,LPR08], extraordinary optical transmission [Nature08,Nature12], light interaction with localized plasmons [PRL13,ACSPhoton21] and picocavities [ACSPhoton21].

Lalanne's designs have set records and introduced groundbreaking performances, including photonic-crystal cavities with tapered mirrors, slow light injectors, directional plasmon launchers, and broadband single-channel photon sources. He pioneered the field of metasurfaces in the 1990s, demonstrating the first metalenses with both large numerical apertures and high efficiencies (>80%) [JOSAA99,LPR17], laying the groundwork for many modern designs. He is currently working on optical disordered metasurfaces to control the appearance of diffusive metasurfaces [NatMater22].

He has supervised 17 PhD candidates and co-supervised 6 more. Lalanne serves on the editorial boards of Laser & Photonics Reviews, Advanced Optical Materials and Photonics Insights. His accolades include the CNRS Bronze medal in 1993, the prix Fabry de Gramont in 1998, and the Grand Prix Léon Brillouin of the Société Française d’Optique in 2024. He was awarded an Advanced ERC Grant in 2023 . He is a fellow of the IOP, OPTICA and SPIE.