Nonlinear Mode Coupling Coefficient Extraction In Atomically Thin Mos2 Nanoelectromechanical Resonators

This digest paper reports on the first experimental demonstration of measuring the nonlinear mode coupling coefficient (λ) due to 1:1 internal resonance from the first-principles approach in a bilayer (2L) molybdenum disulfide (MoS
2
) nanoelectromechanical resonator. We calibrate the vibration amplitude of both modes in the displacement domain by measuring the undriven thermomechanical noise. To extract λ, we drive mode 2 at f
drv
, record its amplitude (a
2
), and measure the resonance frequency of mode 1 (f
1
) excited by energy transferring from mode 2 to mode 1 due to nonlinear mode coupling. We plot f
1
vs a
2
and extract λ=2.137×10
¹⁷
kg•m
^-2
•s
^-2
and 2.185×10
¹⁷
kg•m
^-2
•s
^-2
for f
drv
=20.5 MHz and 20.6 MHz, respectively, by fitting the experimental data. This approach provides a direct means of extracting λ in nanoelectromechanical systems (NEMS) and will be valuable for understanding nonlinear mode coupling and internal resonances in ultrasmall resonant NEMS.