The knowledge sharing seminar by

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Assoc. Prof. Hai-Son Nguyen

Institut des Nanotechnologies de Lyon
Ecole Centrale de Lyon

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Assoc. Prof.  Hai-Son Nguyen

Enriching your research ideas, motivating yourself on the academic path, and building new research collaborations are the targets of our knowledge-sharing seminars. You are most welcome to our knowledge-sharing seminar this month presented by Assoc. Prof. Hai-Son Nguyen. Although Hai-Son is a young researcher and educator, he has achieved numerous fruitful and excellent research.

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Title: Teaching light appearance new tricks in the subwavelength scale: how to shape photonic band on-demand and taming their losses at will

Abstract: 

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Tailoring resonances has always been at heart of modern photonics:  nurturing photons for cavity-quantum electrodynamics, minimizing attenuation of guided light in integrated circuit and optical fiber, sharpening photonic resonances for low-threshold lasing and high-sensitivity optical sensing, engineering emission pattern of light-emitting diodes via radiation-mode out-coupling, to cite a few examples. In “ordered” nanostructures, the “appearance” of photonic resonances is given by the complex energy-momentum band structure of which the real-part corresponds to photon frequency and the imaginary-part corresponds to photon losses. This “appearance” molds light propagation, dictates light coupling with free space, and tailors light-matter interactions mechanisms.

In this presentation. we will first introduce the concept of photonic band structure in photonic crystals via analogy with text-book notions of electronic band structures in solid crystals. Then we will discuss different novel concepts to harness these dispersion characteristics.  To illustrate the engineering of the real-part, we show that the same photonic band can transform continuously from Dirac dispersion to flatband in a simple photonic structure, or undergo a series of magic flatband configurations in moiré superlattice. Moreover, when taking into account the losses in open system, we can control photonic losses to engineer exotic phenomena such as exceptional points, and bound states in the continuum. All of these concepts will be illustrated by experimental demonstrations. Finally, for applications, we will present some proof-of-concepts of original micro-lasers and optical trappings based-on non-Hermitian singularity.

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Biography:

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Hai Son Nguyen is an experimental and theoretical physicist specialized in nanophotonics, quantum optics and condensed matter physics. He holds a degree in Physics (2009) of École Normale Superieure de Paris (ENS Paris). He obtained a PhD degree in Physics (2011) with his works on ultra-coherent single photons emission of semiconductor quantum dots at ENS Paris. From 2011-2014, he was CNRS postdoctoral researcher, working on half-light/half-matter quasiparticles to explore quantum fluid of light and analog black hole in laboratory. Just after the first postdoctoral position, he got the Tenure Associate professor at École Centrale de Lyon in 2014. He is also fellow member of Institut Universitaire de France (IUF, Academic Institute of France) for the period 2020-2025. His teaching includes lectures on electronics, quantum information and quantum engineering. His research is carried out at the Lyon Institute of Nanotechnology (Institut des Nanotechnologies de Lyon, INL).  He is interested in both fundamental research and technological applications. His current research focus on the manipulation and control of light-matter interaction for studying new regime of nanophotonics and quantum optics, with three main research activities:

• Novel concepts of optical lattice and metasurface: light confinement in moiré structures, non-hermitian photonics and topological photonics.

• Perovskite-based emitting devices: implementation of nanophotonic design to improve performance of perovskite LEDs and lasers in the weak coupling regime; and to study exciton polariton features in the strong coupling regime.

• Single photon emitters in silicon platform at telecom wavelength band:  III-V quantum dots in nanowires grown on silicon substrate; deterministic defects in silicon nano structures.

His research has been published in high-impact journals such as Nature, Nature Materials, Nature Communications, Physical Review Letters, Nano Letters, Advanced Energy Materials, Advanced Optical Materials … with an h-factor of 18. He has supervised 3 Postdoctoral researchers, 7 PhD students and 23 master students. He has organized 3 international conferences and also participated in many outreach events to promote science to broad audience.

Major fundings that Hai Son Nguyen has been granted:

MetaLEDs (Perovskite MetaLeds: a smart lighting device over conventional light-emitting diodes for electric vehicle’s lighting and ultra-high resolution displays)

Funding source: VinF (2021-2024)

Amount: 167kEu 

Role: Co PI

TORE (Topological revolution)

Funding source: IDEX Lyon- Scientific Breakthrough (2019-2022)

Amount:  1.2 MEu

Role: Co PI

POPEYE (Polaritonic physics with perovskite in photonic crystal)

Funding source: ANR JCJC (2017-2022)

Amount:  301 kEu

Role: Sole PI

EMIPERO (Electrically pumped hybrid perovskites based light-emitting devices)

Funding source: ANR PRC (2018-2022)

Amount: 486 kEu

Role: Responsible for optical design and characterization of devices with photonic crystal concepts

IPPON (Incoherent light and Phonon management in micro-nanopatterned materials for efficient depollution and artificial Photosynthesis)

Funding source: IDEX Lyon- Scientific Breakthrough (2018-2021)

Amount: 1.2 MEu

Role: Responsible for optical design and characterization

PICSEL (Photonic Integrated CMOS compatible Surface-and-Edge emitting Laser)

Funding source: ANR PRC (2015-2019)

Amount: 800 kEu

Role: Responsible for design and characterization of steerable micro-laser

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Time: 22 October 2022, 9:00 AM Paris time

Zoom link: https://lu-se.zoom.us/j/64527653947

Chairman: Assoc. Prof. Ngoc-Diep Lai