Measuring Frequency Fluctuations in Nonlinear Nanomechanical Resonators
Measuring Frequency Fluctuations in Nonlinear Nanomechanical Resonators
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DOI：
10.1021/acsnano.8b01634
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发表时间：
2018-06-01
期刊：
影响因子：
17.1
通讯作者：
Collin, Eddy
中科院分区：
文献类型：
--
作者：
Maillet, Olivier;Zhou, Xin;Collin, Eddy
近年来，纳米力学的进展已经证明了一个不断扩大的设备范围，从自上而下的结构到吸引人的自下而上的二硫化钼和石墨烯膜，用于传感和面向组件的应用。所有这些器件的主要问题之一是频率噪声，这最终限制了它们的适用性。这个问题最近引起了很多关注，这种噪音的起源至今仍然难以捉摸。在这篇文章中，我们提出了一个非常简单的技术来测量非线性机械设备中的频率噪声，基于双稳态的存在。这是说明氮化硅高应力双固支梁，在低温环境中。我们报告相同的T/f依赖的频率噪声功率谱的文献中报道的。但我们也发现了意想不到的阻尼波动，放大在附近的分叉点，这种效果是明显不同于已经报道的非线性失相，并提出了一个基本的限制分叉频率的测量。该技术进一步应用于测量频率噪声作为模式数的函数，在同一设备内。基本弯曲Δ f/f（0）的相对频率噪声在0.5-0.01 ppm的范围内（与低温MHz器件的文献一致），并且在所研究的范围内随模态数而减小。该技术可以应用于任何类型的纳米机械结构，使这些设备中的固有噪声源的理解取得进展。
Advances in nanomechanics within recent years have demonstrated an always expanding range of devices, from top-down structures to appealing bottom-up MoS2 and graphene membranes, used for both sensing and component-oriented applications. One of the main concerns in all of these devices is frequency noise, which ultimately limits their applicability. This issue has attracted a lot of attention recently, and the origin of this noise remains elusive to date. In this article we present a very simple technique to measure frequency noise in nonlinear mechanical devices, based on the presence of bistability. It is illustrated on silicon-nitride high-stress doubly clamped beams, in a cryogenic environment. We report on the same T/f dependence of the frequency noise power spectra as reported in the literature. But we also find unexpected damping fluctuations, amplified in the vicinity of the bifurcation points; this effect is clearly distinct from already reported nonlinear dephasing and poses a fundamental limit on the measurement of bifurcation frequencies. The technique is further applied to the measurement of frequency noise as a function of mode number, within the same device. The relative frequency noise for the fundamental flexure delta f/f(0) lies in the range 0.5-0.01 ppm (consistent with the literature for cryogenic MHz devices) and decreases with mode number in the range studied. The technique can be applied to any type of nanomechanical structure, enabling progress toward the understanding of intrinsic sources of noise in these devices.