DOI: 10.5061/dryad.63xsj3vcq
title: Data from: Acoustic wave modulation of gap plasmon cavities

description: 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 ultraconfi ned geometries.
description: # Data from: Acoustic wave modulation of gap plasmon cavities
 *Corresponding manuscript*: “Acoustic Wave Modulation of
 Gap Plasmon Cavities,” submitted to **Science**. This repository contains
 all data, code, and simulation files required to reproduce the figures in
 the manuscript. *Software versions*: **MATLAB R2023a**,
 **COMSOL Multiphysics 5.6**. *Units*: SI unless otherwise noted. File and
 folder names appear in monospace. --- ### Data_for_Fig_1.zip *
 `Matlab_sigma_sc_plotting.m` *MATLAB script that plots the scattering
 cross section versus gap size and wavelength.* *
 `NPoMsym15_lam_solve_5.3E-7_gap_4E-9_theta_0_facet_size_4E-8.mph` *
 `NPoMsym15_lam_solve_6.7E-7_gap_4E-9_theta_0_facet_size_4E-8.mph` *COMSOL
 5.6 optical frequency‑domain simulations of the NPoM structure at normal
 incidence. Each file contains the full solution for a single wavelength,
 gap size, and facet size (all encoded in the filename).* *
 `NPoMsym15_lam_solve_5p3Em7_gap_4Em9_theta_0_facet_size_4Em8.java` *
 `NPoMsym15_lam_solve_5p3Em7_gap_4Em9_theta_0_facet_size_4Em8.m` *Java and
 MATLAB model files of
 `NPoMsym15_lam_solve_5.3E-7_gap_4E-9_theta_0_facet_size_4E-8.mph`.* *
 `NPoMsym15_lam_solve_6p7Em7_gap_4Em9_theta_0_facet_size_4Em8.java` *
 `NPoMsym15_lam_solve_6p7Em7_gap_4Em9_theta_0_facet_size_4Em8.m` *Java and
 MATLAB model files of
 `NPoMsym15_lam_solve_6.7E-7_gap_4E-9_theta_0_facet_size_4E-8.mph`.* *
 `sigma_sc_TM__ALL.txt` Numerical optical results for **700** simulations.
 | Column | Description | | :----: | --------------------------------- | |
  1  | Free‑space wavelength (m) | |  2  | Gap size (m) | |  3  |
 **(unused; all zeros)** | |  4  | Facet size (m) — constant 40 nm | |  5 
 | **(unused; all zeros)** | |  6  | **Scattering cross-section (m²)** |
 --- ### Data_for_Fig_2.zip * `2D SAW - dispersion with full metal
 covering.mph` *COMSOL eigenfrequency simulation of the Y-Z LiNbO₃
 surface-acoustic-wave (SAW) mode with full metal coverage (Fig. 2B).* *
 `twoD_SAW_dispersion_with_full_metal_covering.java` *
 `twoD_SAW_dispersion_with_full_metal_covering.m` *Java and MATLAB model
 files of `2D SAW - dispersion with full metal covering.mph`* *
 `ChirpIDT_PML_230519.mph` *COMSOL electro‑mechanical frequency‑domain
 simulation of the complete device, including the interdigitated transducer
 (IDT) and metal films.* * `ChirpIDT_PML_230519.java` *
 `ChirpIDT_PML_230519.m` *Java and MATLAB model files of
 `ChirpIDT_PML_230519.mph`.* * `ChirpedIDT_PML_AllProbeData_230519.txt`
 *Surface-displacement probe data exported from the file above.* Column 7
 gives the out‑of‑plane displacement at a point adjacent to the IDT,
 corresponding to the region probed optically (plotted as the
 **Simulation** trace in Fig. 2C). *
 `SAW_IDT_transducers_acoustic_sim_plotting_230519.m` *MATLAB script that
 imports experimental surface‑displacement measurements, compares them with
 the simulated displacements in `ChirpedIDT_PML_AllProbeData_230519.txt`,
 and generates Fig. 2C.* --- ### Data_for_Fig_3.zip *
 `Time_resolved_spectra_and_peak_plasmon_resonance_V2.m` *MATLAB script
 that plots the time-resolved spectra for the SOR and FOR modes.* *
 `Gap_size_projections_250220.m` *Converts the plasmon‑resonance wavelength
 (λ₁₁) to instantaneous gap size using a COMSOL mapping similar to
 Fig. 1D.* * `time_and_peaks_of_NP133_231106_chop2500.mat` *Contains
 time‑vs‑peak plasmon‑resonance wavelength (λ₁₁) data produced by the
 time‑resolved spectra plotting script for the SOR.* *
 `time_and_peaks_of_NP133_231106_TCSPC.mat` *Contains time‑vs‑peak
 plasmon‑resonance wavelength (λ₁₁) data produced by the time‑resolved
 spectra plotting script for the FOR.* *
 `Matlab_spectrum_plotting_RFoff_vs_RFon_231206.m` *Plots the time‑averaged
 spectrum (Fig. 3D).* * **`sigma_sc_TE__ALL.txt`** *Numerical optical
 results for **1,488** simulations.* | Column | Description | | :----: |
 --------------------------------- | | 1 | Free‑space wavelength (m) | | 2
 | Gap size (m) | | 3 | **(unused; all zeros)** | | 4 | Refractive index of
 gap filler | | 5 | **(unused; all zeros)** | | 6 | **Scattering
 cross‑section (m²)** | * `Picoharp T2 data 231106/*.txt` *Raw
 time‑correlated single‑photon counting (TCSPC) data acquired in T2/TTTR
 mode (SOR). Each file is a text file with four columns. Each row
 represents the detection of a single sync event or photon. Channel 0 is
 the sync channel synchronized with the RF power chopping signal. Channel 1
 is connected to a single‑photon avalanche detector that detects photons
 from a single NPoM. Filename parameters: sample name = LNw21s16; NPoM name
 = NP133; SAW frequency = 670 MHz; SAW power‑chopping frequency = 2,500 Hz;
 optical illumination wavelength = 500 to 700 with 10nm step size.* |
 Column | Description | | :----: | ------------------------------------- |
 | 1 | Event number | | 2 | **(unused; reads “CHN”)** | | 3 | Channel
 number | | 4 | Time at which the event occurred (ps) | * `Picoharp T2 data
 231106/T2_matlab_analysis_flexable.m` *Wraps raw time‑correlated T2 photon
 events around the sync signals, generating the periodic optical signal,
 and exports `NP133_SAWfreq_670MHz_chop2500Hz_cycleDiv5000.mat`.* *
 `Picoharp T2 data 231106/NP133_SAWfreq_670MHz_chop2500Hz_cycleDiv5000.mat`
 *MATLAB data file for the periodic optical signal of a single NPoM
 (NP133). The variable `all_cnts` contains all 21 wavelengths at which the
 periodic T2 optical signal was acquired. The 400‑µs period (1/2500 Hz) is
 divided into 5,000 bins.* * `Picoharp TCSPC data 231106/*.mat` *Raw TCSPC
 data for the fast optical response (FOR). Each file is a `.mat` file with
 a single variable named `output` that contains time in one column and
 optical counts in the other. Filename parameters: sample name = LNw21s16;
 NPoM name = NP133; SAW frequency = 670 MHz; optical illumination
 wavelength = 500 to 700 with 10nm step size.* * `Picoharp TCSPC data
 231106/NP133_231106_TCSPC.gif` *Animated GIF of the optical scattering
 spectrum (FOR).* * `Picoharp TCSPC data
 231106/TCSPC_matlab_analysis_flexable.m` *Compiles all raw TCSPC `.mat`
 files into a single data file containing all optical wavelengths and
 signal amplitudes: `NP133_TCSPC_SAWfreq_670.mat`.* * `Picoharp TCSPC data
 231106/NP133_TCSPC_SAWfreq_670.mat` *Data file containing all optical
 wavelengths and signal amplitudes from the raw `.mat` files.* * `spectrum
 data 231106/` *Raw time‑averaged spectra (Fig. 3D) acquired with a grating
 spectrometer.* * `spectrum data 231106/ref75_z0_10s_from_231031 015.csv`
 *Time‑averaged spectrum of the lamp.* * `spectrum data
 231106/dark_100s_from_231031 014.csv` *Time‑averaged dark‑current
 spectrum.* * `spectrum data 231106/NP133_rfoff_100s 009.csv` * `spectrum
 data 231106/NP133_rfoff_100s 011.csv` *Time‑averaged spectrum of NP133
 with the SAW RF power off (no acoustic wave).* * `spectrum data
 231106/NP133_670MHz_100s 010.csv` * `spectrum data
 231106/NP133_670MHz_100s 012.csv` *Time‑averaged spectrum of NP133 with
 the SAW RF power on (acoustic wave active).* * `spectrum data
 231106/NP133_backgnd_100s 013.csv` *Time‑averaged spectrum of the planar
 gold film adjacent to NP133. This is defined as the background spectrum
 for NP133.* * `spectrum data 231106/NP133_670MHz_expNum_12_bckgnd.mat` *
 `spectrum data 231106/NP133_670MHz_expNum_12_no_bckgnd.mat` * `spectrum
 data 231106/NP133_RFoff_expNum_11_bckgnd.mat` * `spectrum data
 231106/NP133_RFoff_expNum_11_no_bckgnd.mat` *Time‑averaged spectra at the
 21 wavelengths at which the time‑resolved spectrum was measured. `bckgnd`
 indicates the spectrum includes the background signal; `no_bckgnd`
 indicates the background has been subtracted.* --- ### Data_for_Fig_4.zip
 * `Full_equn_solve_lin_spr_and_lin_asym_vis_240823.m` *MATLAB script that
 implements both the nonlinear and linear spring–dashpot (with asymmetric
 drag) models used to generate Fig. 4D.* *
 `Matlab_analysis_oneArea_240823.m` *Analysis script used to create
 Fig. 4E. Dark‑field videos of multiple NPoMs\ are processed with a 1 Hz
 lock‑in technique to extract the SOR amplitude versus SAW frequency or
 power.* * `LNw21s14_freq_sweep_100to800MHz_005_ver2.avi` *Video of a
 frequency sweep from 100 MHz to 800 MHz (linear in time).* *
 `LNw21s14_pow_sweep_550MHz_005_stable.avi` *Video of a power sweep from
 –30 dBm to +3 dBm (linear in time, logarithmic power scale).* *
 `Pchip_vs_PznbdBm_550MHz.mat` *Calibration table mapping RF‑source output
 power to the power delivered to the IDT, compensating for amplifier
 nonlinearity.* **Helper functions** (required by
 `Matlab_analysis_oneArea_240823.m`): * `Pznb_dBm_2_Pchip.m` *
 `oneArea_noMask_simulStart_240823.m` * `readAVI.m` --- *
 `movie_S1_uncut.avi` *Full-length, raw (unstabilized) Movie S1 acquired as
 a fast time-lapse in NIS-Elements AR. The surface acoustic wave is toggled
 on and off at 1 Hz while its frequency is continuously swept from 100 MHz
 to 1 GHz over ~350 s. The focus was manually adjusted throughout the
 recording to compensate for drift.* ### Contact For questions, please
 contact the corresponding authors at\
 [selvin@stanford.edu](mailto:selvin@stanford.edu) •
 [brongersma@stanford.edu](mailto:brongersma@stanford.edu)