Thickness-Dependent Surface Phonon Polaritons in InSe

Published

May 21, 2026

Author(s)

Thuc Mai, Michael Altvater, Viktor Labuntsov, Sergiy Krylyuk, Albert Davydov, Michael Susner, Nguyen Tuan Hung, Jason Lynch, Deep Jariwala, Michael Snure, Riichiro Saito, Vasili Perebeinos, Nicholas Glavin, Rahul Rao

Abstract

Two-dimensional (2D) materials are promising platforms for phonon polaritons (PhPs)—hybrid modes arising from photon-phonon interactions—that enable subwavelength light confinement and optoelectronic functionalities. γ-indium selenide (γ-InSe), an emerging 2D semiconductor with thickness-dependent optoelectronic properties, offers a unique system to explore confined surface phonon polaritons (SPhPs). Here, we employ tilt angle-dependent resonant Raman spectroscopy to measure SPhPs in γ-InSe flakes with thicknesses from 10 nm to 1.2 μm, exfoliated on SiO2 and sapphire substrates. We observe a pronounced thickness-dependent dispersion of the polar A1(TO) phonon mode, with a maximal slope near 100-nm thickness, corresponding to the inverse absorption coefficient. Moreover, differences in the polariton dispersion on SiO2 and sapphire show a dependence on the dielectric environment. The dispersions align with calculations modeling the flakes as Fabry-Perot cavities supporting confined SPhPs. These findings advance our understanding of light-matter interactions in γ-InSe and highlight the potential for their use in nanophotonic devices.

Citation

Matter & Light

Volume

1

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.matlit.2026.100014

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Keywords

2D materials, surface phonon polaritons, Raman spectroscopy

Citation

Mai, T. , Altvater, M. , Labuntsov, V. , Krylyuk, S. , Davydov, A. , Susner, M. , Tuan Hung, N. , Lynch, J. , Jariwala, D. , Snure, M. , Saito, R. , Perebeinos, V. , Glavin, N. and Rao, R. (2026), Thickness-Dependent Surface Phonon Polaritons in InSe, Matter & Light, [online], https://doi.org/10.1016/j.matlit.2026.100014, https://nps-ext.nist.gov/nps/nps_public_api/api/Publication/file/961183 (Accessed October 27, 2026)

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