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Publications
Skyler P Selvin; Majid Esfandyarpour; Anqi Ji; Yan Joe Lee; Colin Yule; Jung-Hwan Song; Mohammad Taghinejad; Mark L Brongersma
Acoustic wave modulation of gap plasmon cavities Journal Article
In: Science, vol. 389, iss. 6759, pp. 516-520, 2025.
@article{selvin2025acoustic,
title = {Acoustic wave modulation of gap plasmon cavities},
author = {Skyler P Selvin and Majid Esfandyarpour and Anqi Ji and Yan Joe Lee and Colin Yule and Jung-Hwan Song and Mohammad Taghinejad and Mark L Brongersma},
url = {https://brongersma.stanford.edu/wp-content/uploads/2025/08/science.adv1728-2.pdf
https://www.science.org/stoken/author-tokens/ST-2800/full},
doi = {10.1126/science.adv1728},
year = {2025},
date = {2025-07-31},
urldate = {2025-07-31},
journal = {Science},
volume = {389},
issue = {6759},
pages = {516-520},
abstract = {The important role of metallic nanostructures in nanophotonics will expand if ways to electrically manipulate their optical resonances at high speed can be identified. We capitalized on electrically driven surface acoustic waves and the extreme light concentration afforded by gap plasmons to achieve this goal. We placed gold nanoparticles in a particle-on-mirror configuration with a few-nanometer-thick, compressible polymer spacer. Surface acoustic waves were then used to tune light scattering at speeds approaching the gigahertz regime. We observed evidence that the surface acoustic waves produced mechanical deformations in the polymer and that ensuing nonlinear mechanical dynamics led to unexpectedly large levels of strain and spectral tuning. Our approach provides a design strategy for electrically driven dynamic metasurfaces and fundamental explorations of high-frequency, polymer dynamics in ultraconfined geometries.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The important role of metallic nanostructures in nanophotonics will expand if ways to electrically manipulate their optical resonances at high speed can be identified. We capitalized on electrically driven surface acoustic waves and the extreme light concentration afforded by gap plasmons to achieve this goal. We placed gold nanoparticles in a particle-on-mirror configuration with a few-nanometer-thick, compressible polymer spacer. Surface acoustic waves were then used to tune light scattering at speeds approaching the gigahertz regime. We observed evidence that the surface acoustic waves produced mechanical deformations in the polymer and that ensuing nonlinear mechanical dynamics led to unexpectedly large levels of strain and spectral tuning. Our approach provides a design strategy for electrically driven dynamic metasurfaces and fundamental explorations of high-frequency, polymer dynamics in ultraconfined geometries.
Burak Aslan; Colin Yule; Yifei Yu; Yan Joe Lee; Tony F. Heinz; Linyou Cao; Mark L. Brongersma
Excitons in strained and suspended monolayer WSe2 Journal Article
In: 2D Materials, vol. 9, no. 1, pp. 015002, 2021.
@article{aslan2021excitons,
title = {Excitons in strained and suspended monolayer WSe2},
author = {Burak Aslan and Colin Yule and Yifei Yu and Yan Joe Lee and Tony F. Heinz and Linyou Cao and Mark L. Brongersma},
doi = {10.1088/2053-1583/ac2d15},
year = {2021},
date = {2021-10-21},
urldate = {2021-10-21},
journal = {2D Materials},
volume = {9},
number = {1},
pages = {015002},
abstract = {We study suspended membranes of atomically thin WSe2 as hosts of excitons. We perform optical reflectance measurements to probe the exciton physics and obtain the peak energies for the 1$s$, 2$s$, and 3$s$ states of the $A$ exciton in suspended WSe2 and consider supported membranes as a reference. We find that elimination of the influence of the dielectric environment enables a strong electron\textendashhole interaction and a concomitant increase in the exciton binding energy in suspended monolayer (1L) WSe2. Based on the experimental results, we calculate the excitonic binding energies by employing the recently developed quantum electrostatic heterostructure model and the commonly employed Rytova\textendashKeldysh potential model. We see that the binding energy of the ground state $A$ exciton increases from about 0.3 eV (on a substrate) to above 0.4 eV (suspended). We also exploit the tunability of the excitons in suspended samples via mechanical strain. By applying external gas pressure of 2.72 atm to a 1L suspended over a circular hole of 8 μm diameter, we strain the WSe2 and obtain a reversible 0.15 eV redshift in the exciton resonance. The linewidth of the $A$ exciton decreases by more than half, from about 50 to 20 meV under 1.5% biaxial strain at room temperature. This line narrowing is due to the suppression of intervalley exciton\textendashphonon scattering. By making use of the observed strain-dependent optical signatures, we infer the two-dimensional (2D) elastic moduli of 1L and 2L WSe2. Our results exemplify the use of suspended 2D materials as novel systems for fundamental studies, as well as for strong and dynamic tuning of their optical properties.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We study suspended membranes of atomically thin WSe2 as hosts of excitons. We perform optical reflectance measurements to probe the exciton physics and obtain the peak energies for the 1$s$, 2$s$, and 3$s$ states of the $A$ exciton in suspended WSe2 and consider supported membranes as a reference. We find that elimination of the influence of the dielectric environment enables a strong electron–hole interaction and a concomitant increase in the exciton binding energy in suspended monolayer (1L) WSe2. Based on the experimental results, we calculate the excitonic binding energies by employing the recently developed quantum electrostatic heterostructure model and the commonly employed Rytova–Keldysh potential model. We see that the binding energy of the ground state $A$ exciton increases from about 0.3 eV (on a substrate) to above 0.4 eV (suspended). We also exploit the tunability of the excitons in suspended samples via mechanical strain. By applying external gas pressure of 2.72 atm to a 1L suspended over a circular hole of 8 μm diameter, we strain the WSe2 and obtain a reversible 0.15 eV redshift in the exciton resonance. The linewidth of the $A$ exciton decreases by more than half, from about 50 to 20 meV under 1.5% biaxial strain at room temperature. This line narrowing is due to the suppression of intervalley exciton–phonon scattering. By making use of the observed strain-dependent optical signatures, we infer the two-dimensional (2D) elastic moduli of 1L and 2L WSe2. Our results exemplify the use of suspended 2D materials as novel systems for fundamental studies, as well as for strong and dynamic tuning of their optical properties.
