Research

1. Molecular strong coupling and polaritons

When molecules exchange energy with light confined in a cavity or on a metal surface faster than either loses it, they form hybrid light–matter states called polaritons. During my PhD and postdoctoral research at the University of Exeter, United Kingdom, I explored these states across the mid-infrared, where molecular vibrations couple to light, and the visible, where molecular excitons do.

Mid-infrared: vibrational strong coupling

• Local ultrastrong coupling revealed by surface-enhanced Raman spectroscopy of open metallic gratings, with the lower polariton localised in the grating slots. Physical Review Letters (2023)

• Wavelength-modulated Raman spectroscopy that suppresses fluorescence backgrounds when probing vibrational strong coupling. Advanced Optical Materials (2021)

• Strong coupling to modes beyond the light line in metal-clad and Bragg-mirror microcavities. ACS Photonics (2020)

• Surface plasmons on gold gratings as open cavities for vibrational strong coupling, including surface-plasmon stop bands. ACS Photonics (2019)

• Hybridisation of three vibrational modes of one molecule through a single cavity mode. Advanced Optical Materials (2019)

• Infrared and Raman study of strongly coupled vibrational modes. OSA Technical Digest (2016)

Visible: excitonic strong coupling

• The role of cavity finesse in molecular strong coupling, comparing open, half and full planar cavities (invited). The Journal of Physical Chemistry Letters (2024)

• Room-temperature ultrastrong coupling in a simple film of dye molecules, without an external cavity. The Journal of Physical Chemistry Letters (2021)

• Polariton-assisted photoemission from a layered J-aggregate material, and the roles of vibrational states and molecular absorption. Nanoscale (2021)

2. Mathematical modelling, topology and cavity theory

Much of my work rests on mathematical models that I develop and test against experiment: coupled-oscillator eigenvalue problems for multimode light–matter coupling, transfer-matrix and Fourier-modal descriptions of waves in layered and periodic media, and finite-element and boundary-element models of nanostructures.

• Phase singularities created by strong coupling, located as winding-number zeros of the complex reflection ratio and switched on and off with light. Nature Communications (2022)

• A multimode theory of cavity emission that sets a quantitative finesse criterion for strong coupling. The Journal of Physical Chemistry Letters (2024)

• Eigenvector (Hopfield) analysis of multimode polaritons and wave dispersion beyond the light line. Advanced Optical Materials (2019); ACS Photonics (2020)

3. Plasmonic photocatalysis and single-particle optical metrology

Since 2023 at Monash University, my research has centred on light-driven chemistry, first with Prof. Stefan Maier in Physics and Astronomy and now with Prof. Akshat Tanksale and Prof. Murali Sastry in Chemical and Biological Engineering. I treat each catalyst particle as an optical antenna and ask which of its optical modes drives the chemistry. Using a single-particle dark-field microscopy facility built around a supercontinuum laser, I link the structure and composition of individual bimetallic nanoparticles to their optical response and catalytic activity, and with wavelength-resolved action spectroscopy I connect reaction rates to specific plasmon modes. This work focuses on visible-light CO₂ conversion within the ARC Research Hub for Carbon Utilisation and Recycling (RECARB) and the Woodside Monash Energy Partnership.

• Correlative dark-field spectroscopy and STEM-EDS of single bimetallic nanoparticles, linking composition to plasmon damping (first author). The Journal of Physical Chemistry C (2025)

• Visible-light CO₂ hydrogenation on surface-alloyed AgPt nanoprisms, with wavelength-resolved action spectroscopy. EES Catalysis (2025)

• Reaction-driven active configurations of single-atom catalysts for CO₂ electroreduction. Nano Energy (2024)

• Lead-free halide perovskite–plasmonic hybrids for visible-light CO₂ reduction, with A/Prof Lling-Lling Tan, Monash University Malaysia (2026)

• Anomalous small-angle X-ray scattering (Australian Synchrotron) and contrast-matched neutron scattering (ANSTO) to resolve element distribution inside bimetallic nanocrystals (2026)

• Solar-thermal desalination with porous alumina–silver nanofluids, in an Australia–India Strategic Research Fund project with IIT Bombay

4. Two-dimensional materials, nonlinear optics and nanofabrication

• Enhanced third- and fifth-harmonic generation in graphene heterostructures with plasmonic nanoribbons. Advanced Optical Materials (2022)

• Two-photon polymerisation lithography for imaging optics, a topical review. International Journal of Extreme Manufacturing (2024)

5. Current direction: quantum light sources

Building on cavity design and single-particle spectroscopy, I am developing nanophotonic structures that make room-temperature single-photon emitters in two-dimensional materials brighter and more directional, including through an IITB–Monash Research Academy PhD project. Details of open projects are on the Opportunities page.

Methods and facilities

• Spectroscopy: single-particle dark-field, angle-resolved and Fourier-plane, FTIR, Raman and wavelength-modulated Raman, photoluminescence, OPTIR

• Fabrication: electron-beam lithography and two-photon lithography

• Characterisation: SEM, STEM-EDS and AFM

• Modelling: coupled-oscillator theory, transfer-matrix and Fourier modal (RCWA) methods, COMSOL Multiphysics (FEM), Lumerical FDTD and BEM, with analysis in Python and MATLAB