Hai Son Nguyen

Associate Professor at École Centrale de Lyon (ECL)
Institut des Nanotechnologies de Lyon (INL), France
CNRS International NTU–Thales Research Alliance (CINTRA) , Singapore

✨ Open Positions
I am currently recruiting PhD students and Postdoctoral Researchers to work on projects between Lyon (INL–CNRS) and Singapore (CINTRA/NTU), in areas including:

Non-Hermitian and topological photonic crystal slabs
Moiré and bilayer photonic architectures
Perovskite metasurfaces and polaritonics
Quantum emitters and quantum nanophotonics
Strong light–matter interaction & room-temperature polaritons

If you are interested, please send a CV and a short motivation email to: hai-son.nguyen@ec-lyon.fr.

Research Themes

Our group develops photonic platforms where radiation, topology, excitons, and nanoscale confinement are brought together in controlled and often unconventional ways.

We work across the full spectrum from fundamental wave physics to the realization of practical devices. This includes uncovering new physical mechanisms in non-Hermitian and topological photonics, exploring moiré photonic architectures, and studying exciton–polariton effects at room temperature.

By combining theory, modelling, nanofabrication, and optical spectroscopy, we aim to both advance our understanding of light–matter interaction and develop architectures for lasers, metasurfaces, and quantum-emitter systems.

Theme 1 · Optical Lattices & Non-Hermitian / Topological Physics

Exceptional Points, BICs and moiré photonic crystals

We explore optical lattices in which radiative coupling and interference play an essential structural role. Within this non-Hermitian framework, photonic crystal slabs support controllable Exceptional Points and Bound States in the Continuum. We extend these concepts to multilayer and moiré photonic crystals, where interlayer geometry produces flatbands and uncommon localization. Synthetic momentum dimensions then provide a route to breaking time-reversal symmetry and realizing new topological phases.

Synthetic momentum and high-dimensional topology in guided resonances
Moiré “magic” configurations creating flat bands and light localization
Topological control of radiation and polarization textures

Keywords: non-Hermitian photonics, BICs, Exceptional Points, moiré metasurfaces

Theme 2 · Perovskite Metasurfaces & Polaritons

Active metasurfaces for light generation and polaritonics

We use halide perovskites as active materials in nanostructured metasurfaces to realize room-temperature microlasers, LEDs and exciton–polariton systems. The combination of strong excitonic resonances and tailored photonic modes allows us to control dispersion, directionality and polarization of the emitted light.

Directional perovskite microlasers with engineered momentum-space emission
Excitonic metasurfaces supporting robust room-temperature polaritons and long-range propagation
Light-management concepts for efficient perovskite LEDs and optoelectronic devices

Keywords: perovskite metasurfaces, exciton–polaritons, microlasers, light management

Theme 3 · Quantum Emitters, Collective Effects & Quantum Nanophotonics

From single-photon sources to superradiant ensembles

We engineer nanophotonic environments for solid-state quantum emitters such as silicon color centers, quantum dots in nanowires and emitters in 2D materials. Beyond single-emitter control, we investigate collective light–matter effects, where ensembles coupled to tailored modes exhibit superradiance, superfluorescence and other cooperative emission phenomena.

Purcell enhancement and momentum-resolved control of single-photon emission
Strong-coupling platforms based on metasurfaces and photonic crystal cavities
Collective emission in lattices and flatband/BIC structures: superradiance and superfluorescence

Keywords: single-photon sources, silicon defects, nanowires, 2D emitters, superradiance, superfluorescence

These themes combine theory, numerical modelling, nanofabrication, and experiments, and are developed at INL (Lyon) and CINTRA / NTU (Singapore), together with international collaborators.