Like a candle in the wind: flicker noise in nano-optomechanical systems

机械系统，包括纳米机电系统(NEMS)和纳米光学机械系统(NOMS)，其频率稳定性水平对其作为超灵敏传感器和参考振荡器的性能至关重要。最近我们领域的工作表明，这种性能几乎永远不会像人们所希望的那样受到热机噪声的基本噪声源的限制，而是几乎总是受到频率闪烁噪声的限制。最近的一项突破[Roy，Sauer，Westwood-Bachman，Venkatasubramanian，Hiebert(2018)Science 360，eaar5220]确定了一个令人惊讶的结果，即可以通过降低品质因数(增加阻尼)来保持甚至改善精密机械谐振器的性能。频率稳定度的提高似乎与通过周围(阻尼)空气的热传导来抑制这种普遍存在的闪烁噪声有关。在这一突破性工作的基础上，我们试图探索闪烁噪声对NEMS和NOMS频率稳定性的贡献领域。使用空气阻尼、器件尺寸、器件温度系数(可通过内部应力调节)、光机弹簧调谐、光机耦合和温度的调谐旋钮，我们将彻底探索和了解NOMS器件中闪烁噪声的来源，确定两种竞争模型中的哪一种可以解释整个参数空间的噪声。一旦理解清楚，我们将设计设备来最小化和消除这种噪声，以达到NOMS系统的基本噪声水平和最终的频率稳定极限。将空气阻尼及其闪烁抑制通道与高精细度光学机械相结合，即使在高度阻尼的条件下，也可以使NOMS设备进行自振荡。在环境空气中工作的这类NOMS振荡器的最终极限频率稳定性将最终导致传感器技术的深刻进步，例如空气中的单达质谱仪。

The frequency stability level of mechanical systems, including nanoelectromechanical systems (NEMS) and nano-optomechanical systems (NOMS), is of paramount importance to their performance, both as ultrasensitive sensors, and as reference oscillators. Recent work in our field has shown that this performance is almost never limited by the fundamental noise source of thermomechanical noise, as one would desire, but rather is almost always limited by frequency flicker noise. A recent breakthrough [Roy, Sauer, Westwood-Bachman, Venkatasubramanian, Hiebert (2018) Science 360, eaar5220] established the surprising result that precision mechanical resonator performance can be maintained and even improved by reducing quality factor (increasing damping). The improvement in frequency stability with damping seems to be related to suppression of this ubiquitous flicker noise through the thermal conduction of surrounding (damping) air. Following on from this breakthrough work, we seek to explore the realm of flicker noise contribution to NEMS and NOMS frequency stability. Using tuning knobs of: air damping, device dimension, device temperature coefficient (tunable through internal stress), optomechanical spring tuning, optomechanical coupling, and temperature, we will thoroughly explore and understand the source of flicker noise in NOMS devices, identifying which of two competing models explain the noise throughout this parameter space. Once well-understood, we will design devices to minimize and eliminate this noise in order to reach the fundamental noise level, and ultimate frequency stability limit, of NOMS systems. Combining air damping and its flicker mitigation channel with high-finesse optomechanics will allow self-oscillation of NOMS devices even in highly-damped conditions. Ultimate limit frequency stability in such NOMS oscillators that operate in ambient air will ultimately lead to profound advancements in sensor technology, such as single-Da mass spectrometry in air.