Photothermal Responsivity of van der Waals Material-Based Nanomechanical Resonators

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Van der Waals nanomechanical resonators (vdW NMRs) are emerging tools for sensing absorbed laser power.
• Integrating vdW NMRs into Fabry-Pérot (FP) interferometers enhances their photothermal response.
• The displacement-dependent photothermal response of vdW NMRs requires further investigation.

Purpose of the Study:

• To investigate the displacement-dependent photothermal response of vdW NMRs.
• To develop and validate a model for FP-mediated absorptive heating in vdW NMRs.
• To establish a framework for using FP-mediated vdW NMRs as bolometers.

Main Methods:

• Fabrication of electromotively driven niobium diselenide (NbSe2) drumheads on reflective substrates.
• Measurement of photothermal response (resonant frequency shifts) as a function of optical absorption and NMR displacement.
• Development of a FP-mediated absorptive heating model to explain experimental observations.

Main Results:

• The FP-mediated absorptive heating model accurately explains the measured photothermal response variations.
• Few-layer and monolayer NbSe2 drumheads exhibit superior photothermal response magnitude and tuning range compared to other vdW drum-type NMRs at 532 nm.
• The photothermal response magnitude and tuning range of NbSe2 drumheads scale with material thickness.

Conclusions:

• NbSe2 drumheads integrated into FP interferometers offer enhanced photothermal sensing capabilities.
• The study establishes a displacement-based framework for designing bolometers using FP-mediated vdW NMRs.
• Thickness optimization of NbSe2 drumheads is crucial for maximizing bolometer performance.