Cavity-Assisted Coherent Phonon Generation and Control in a WSe₂/Au Structure.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Terahertz (THz) coherent phonons are promising for high-speed, low-energy information processing in advanced electronic devices.
• Efficient control over THz coherent phonon generation remains a significant challenge for practical applications.

Purpose of the Study:

• To investigate THz coherent phonon generation in exfoliated WSe2 flakes on different substrates (Au and Si).
• To understand the influence of WSe2 layer thickness and laser wavelength on phonon generation dynamics.
• To explore the underlying mechanisms responsible for enhanced THz coherent phonon generation.

Main Methods:

• Time-resolved pump-probe spectroscopy was employed to study THz coherent phonon generation.
• Wavelength-dependent and thickness-dependent measurements were performed on WSe2/Au and WSe2/Si structures.
• Numerical simulations, optical reflectance, and Raman spectroscopy were used for analysis and validation.

Main Results:

• A significant enhancement in THz coherent phonon generation was observed in WSe2/Au structures under specific WSe2 thicknesses and laser wavelengths.
• The enhancement was attributed to light-matter interactions within a self-hybridized optical cavity formed by the WSe2 flake.
• Experimental observations were consistent with numerical simulations and spectroscopic measurements.

Conclusions:

• The study demonstrates a viable method for enhancing THz coherent phonon generation in van der Waals materials.
• Light-matter interactions within a WSe2 cavity play a crucial role in optimizing phonon generation.
• These findings provide valuable insights for developing next-generation THz phononic and phonon-integrated devices.