LIGHT-MOLECULE INTERACTION
The way molecules absorb, transfer, emit energy in the form of light can be drastically modified by placing them in optical cavities. The molecule-cavity coupling strength, then, more or less decides the behaviour of molecules. My research spans under this broad umbrella of 'light-matter interaction'. I try to understand the modifications in absorption and emission parameters of molecules when coupled to optical cavities. I utilise both metallic and dielectric cavities to probe the interaction.
Plasmonic Cavities
Surface plasmons, collective charge oscillations at the metal-dielectric interface, are excellent candidates for enhancement of light-molecule interaction. We utilise plasmonic cavities based on noble metal nanostructures to engineer light emission from molecules confined to extremely small cavities - nanocavities. Such cavities show directional emission and complex polarization signatures.
For more information:
Distinguishing SERS from fluorescence: Nano Lett. 2018, 18, 1, 650–655. (A video clip explaining our work)
Directional SERS: Advanced Optical Materials 2019, 7, 1900304.
Dielectric Cavities
Dielectric cavities, also called soft-cavities, support multiple cavity modes with a large figure of merit, making them excellent candidates for boosting light-molecule interaction. Additionally, they can be easily manipulated in a microfluidic environment, can be functionalised, are biocompatible etc. I utilise individual microspheres to probe molecule-cavity interaction both in weak and strong coupling regimes.
​
For more information:
Molecular monolayer strong coupling: Nano Lett. 2020, 20, 3, 1766–1773.
Vectorial polarisation signatures in fluorescence: Advanced Optical Materials 2018, 6, 1801025.
NANO(MICRO) SCALE HEAT CONTROL
Metallic nano (micro)structures generate heat when illuminated with light / driven by electric current due to joule losses. Of late, this heat generation has been utilized by coupling the structures with a photothermal material (material whose refractive index is sensitive to the local temperature). I am now trying to develop microscale heat sources to generate required thermal profiles to utilize them in wavefront engineering, catalysis, etc.