Enhanced Photon–Phonon Interaction in WSe2 Acoustic Nanocavities

Carr, Alex D.; Ruppert, Claudia; Samusev, Anton K.; Magnabosco, Giulia; Vogel, Nicolas; Linnik, Tetiana L.; Rushforth, Andrew W.; Bayer, Manfred; Scherbakov, Alexey V.; Akimov, Andrey V.

Abstract

Acoustic nanocavities (ANCs) with resonance frequencies much above 1 GHz are prospective to be exploited in sensors and quantum operating devices. Nowadays, acoustic nanocavities fabricated from van der Waals (vdW) nanolayers allow them to exhibit resonance frequencies of the breathing acoustic mode up to f ∼ 1 THz and quality factors up to Q ∼ 103. For such high acoustic frequencies, electrical methods fail, and optical techniques are used for the generation and detection of coherent phonons. Here, we study experimentally acoustic nanocavities fabricated from WSe2 layers with thicknesses from 8 up to 130 nm deposited onto silica colloidal crystals. The substrate provides a strong mechanical support for the layers while keeping their acoustic properties the same as in membranes. We concentrate on experimental and theoretical studies of the amplitude of the optically measured acoustic signal from the breathing mode, which is the most important characteristic for acousto-optical devices. We probe the acoustic signal optically with a single wavelength in the vicinity of the exciton resonance and measure the relative changes in the reflectivity induced by coherent phonons up to 3 × 10–4 for f ∼ 100 GHz. We reveal the enhancement of photon–phonon interaction for a wide range of acoustic frequencies and show high sensitivity of the signal amplitude to the photoelastic constants governed by the deformation potential and dielectric function for photon energies near the exciton resonance. We also reveal a resonance in the photoelastic response (we call it photoelastic resonance) in the nanolayers with thickness close to the Bragg condition. The estimates show the capability of acoustic nanocavities with an exciton resonance for operations with high-frequency single phonons at an elevated temperature.

Citation

Carr, A. D., Ruppert, C., Samusev, A. K., Magnabosco, G., Vogel, N., Linnik, T. L., Rushforth, A. W., Bayer, M., Scherbakov, A. V., & Akimov, A. V. (2024). Enhanced Photon–Phonon Interaction in WSe2 Acoustic Nanocavities. ACS Photonics, 11(3), 1147–1155. https://doi.org/10.1021/acsphotonics.3c01601

• Journal Article Type: Article
• Acceptance Date: Feb 13, 2024
• Online Publication Date: Mar 6, 2024
• Publication Date: Mar 20, 2024
• Deposit Date: Mar 13, 2024
• Publicly Available Date: Mar 14, 2024
• Journal: ACS Photonics
• Electronic ISSN: 2330-4022
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 11
• Issue: 3
• Pages: 1147–1155
• DOI: https://doi.org/10.1021/acsphotonics.3c01601
• Keywords: Layers, Phonons, Probes, Resonance structures, Thickness
• Public URL: https://nottingham-repository.worktribe.com/output/32179110
• Publisher URL: https://pubs.acs.org/doi/10.1021/acsphotonics.3c01601