Giant parametric amplification and spectral narrowing in atomically thin MoS2 nanomechanical resonators
Jaesung Lee, Steven W. Shaw, Philip X.‐L. Feng
Abstract
Pre-amplification of ultrasmall signals directly in the mechanical domain and boosting quality (Q) factors in nanoelectromechanical systems (NEMS) are intriguing scientific questions and technical challenges. These are particularly enticing in resonant NEMS enabled by emerging two-dimensional (2D) layered crystals, toward revealing fundamental limits and potential of 2D NEMS in both science explorations and engineering applications. Fortunately, their ultimately thin nature and unconventional elastic properties offer rich opportunities for manipulating oscillations via parametric and nonlinear effects. Here, we report on the experimental demonstration of giant parametric amplification and spectral linewidth narrowing in atomically thin molybdenum disulfide (MoS2) 2D NEMS resonators vibrating at ∼30–60 MHz. Parametric amplification is examined by photothermally modulating the stiffness of each atomic layer resonator at twice its resonance frequency (2f). Thanks to exceptionally efficient parametric effects in these atomically thin membranes, the parametric amplification of undriven thermomechanical resonance leads to giant parametric gains up to 3605 (71 dB) and spectral linewidth narrowing factors up to 1.8 × 105, before the onset of parametric oscillation. The remarkable parametric amplification and spectral narrowing (including effective Q boosting in the sub-threshold regime) in 2D NEMS validated in this study may open new possibilities for creating ultimately thin yet high-performance resonators and oscillators for signal transduction and sensing in classical and quantum engineering applications.