Metals have electrons in the conduction band that can be collectively excited by light to generate a plasmon resonance. These resonances enhance the electromagnetic field at the metal surface. At the same time, metals also host electrons that can undergo interband energy transitions. In a recent cover story published in Advanced Optical Materials, we show that the plasmon resonances and the interband transitions can couple together to form a new entity – a polariton which features both of these seemingly different properties. We demonstrate the polaritons in both nickel thin films and nickel nanoparticles by measuring their optical properties on the nanoscale using electron energy-loss spectroscopy conducted in a transmission electron microscope. The research was conducted in collaboration with Dr. Ihar Faniayeu (kudos for the stunning cover art) and Prof. Alexander Dmitriev from the University of Gothenburg, Sweden.
You can read more about our research in the open access article:
A. Assadillayev, I. Faniayeu, A. Dmitriev, S. Raza,
"Nanoscale engineering of optical strong coupling inside metals"
Adv. Optical Mater. 11, 2201971 (2023)
If you want to know more, feel free to reach out to me at sraz@dtu.dk.