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.

中文翻译：

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原子级薄二硫化钼纳米机械谐振器中的巨参量放大和光谱变窄

直接在机械域中预放大超小信号和提高纳米机电系统 (NEMS) 中的质量 ( Q ) 因子是有趣的科学问题和技术挑战。这些在由新兴二维 (2D) 层状晶体实现的共振 NEMS 中特别诱人，旨在揭示 2D NEMS 在科学探索和工程应用中的基本限制和潜力。幸运的是，它们最终的薄特性和非常规的弹性特性为通过参数和非线性效应操纵振荡提供了丰富的机会。在这里，我们报告了原子级薄二硫化钼（MoS ₂) 2D NEMS 谐振器以 ∼30-60 MHz 振动。通过以两倍的谐振频率 (2 f )光热调制每个原子层谐振器的刚度来检查参量放大。由于这些原子级薄膜中异常有效的参数效应，未驱动的热机械共振的参数放大导致在参数振荡开始之前高达 3605 (71 dB) 的巨大参数增益和高达 1.8 × 10 ^{5的光谱线宽窄化因子。}显着的参量放大和光谱变窄（包括有效Q在本研究中验证的 2D NEMS 中的亚阈值范围内的增强）可能为在经典和量子工程应用中创建最终薄但高性能的谐振器和振荡器用于信号转导和传感开辟了新的可能性。