Nano-optomechanical systems: sense and sense-stability

最近的一项突破[Roy，Sauer，Westwood-Bachman，Venkatasubramanian，Hiebert(2018)Science 360，eaar5220]显示了一个意想不到的结果，即可以通过降低品质因数(增加阻尼)来提高精密机械谐振器的性能。这对振荡器时钟和谐振传感器的未来发展具有深远的影响。特别是，精密谐振器和振荡器不再局限于在真空中运行，而是可以通过在粘性阻尼环境(如空气)中运行来潜在地增强。*本计划将从机械传感和稳定性的这一新范式角度探索影响的途径，称为平带区域。我的长期愿景是实现复杂的、无处不在的超级传感器，如手持呼吸质谱仪。该计划的短期目标将在以下主题中利用该范例。*1)提高非接触原子力显微镜(AFM)的稳定性*我们可以立即应用平带模型来提高频率调制AFM的稳定性、力灵敏度和测量速度。化学反应过程中的原子分辨原子力显微镜是一个重要的前沿领域，它可能会受到这一目标的极大影响。*2)测试光学力学和自振荡的稳定性模型*我们试图探索反馈回路模型的物理与纳米光学机械系统工具箱提供的丰富的信号控制之间的相互作用。后一种系统提供了丰富的耦合和反作用力以及可以调整的相位。我们在上述科学论文中提出的新的平带稳定性模型表明，可以通过选择锁相环参数来减小振荡器相位噪声的标准分量(例如，李森效应)。如果可能，这不仅可以在原子力显微镜、悬臂梁传感器和时钟振荡器的稳定性方面取得突破，而且可以在一般控制理论方面取得突破。*3)在纳米尺度上演示气流自振荡*最后，我们将利用我们新发现的高阻尼稳定性机制来探索使用气流作为直流能源(如口琴)的纳米机械振荡器物理。从现有的纳米光学机械平台出发，流经芯片表面的恒定气流预计会由于流动不稳定性而激发纳米级悬臂梁的自振。由此产生的技术可以提供一种简单、强大的机制来驱动用于时钟或传感器阵列应用的大型纳米级振荡器阵列，例如纳米级质谱仪。

A recent breakthrough [Roy, Sauer, Westwood-Bachman, Venkatasubramanian, Hiebert (2018) Science 360, eaar5220] showed the unexpected result that precision mechanical resonator performance can be improved by reducing quality factor (increasing damping). This has profound implications for future development in oscillator clocks and resonant sensors. In particular, precision resonators and oscillators are no longer limited to operation in vacuum, but could be potentially enhanced by operation in a viscous damping environment (such as air).*******This program will explore impact avenues from this new paradigm viewpoint of mechanical sensing and stability called the flatband regime. My long term vision is the enablement of sophisticated, ubiquitous, super sensors such as hand-held mass-spectrometers of breath. Short-term objectives of the program will take advantage of the paradigm in the following themes.******1) Improving stability in non-contact atomic force microscopy (AFM) ***We can immediately apply the flatband model for improved stability, force sensitivity, and speed of measurement in frequency modulated AFM. Atomic resolution AFM in situ during chemical reactions is one important frontier that could be greatly impacted by this objective.*******2) Testing the stability model for optomechanics and self-oscillation****We seek to explore the interplay of the physics of feedback loop models with the rich variety of signal control available from the nano-optomechanical systems toolbox. The latter systems provide a wealth of coupling and back-action forces and phases that can be tuned. The new flatband stability model in our above science paper implies that standard components of oscillator phase noise (e.g. Leeson effect) may be mitigated through choice of phase-locked loop parameters. If possible, this could lead to breakthroughs not just in stability of AFM, cantilever sensors, and clock oscillators, but in control theory generally.*******3) Demonstrating air-flow self-oscillation at the nanoscale****Finally, we will take advantage of our newfound high-damping stability regime to explore nanomechanical oscillator physics using air streams as a DC energy source (like a harmonica). Starting from existing nano-optomechanical platforms, a constant air-stream flow across a chip surface is anticipated to excite nanoscale cantilevers into self-oscillation due to flow instabilities. The resulting technology could provide a simple, robust mechanism for driving large arrays of nanoscale oscillators for clock or sensor array applications, such as nanoscale mass spectrometry.***