光学介质膜中机械热噪声和能量耗散的测量
Measurements of mechanical thermal noise and energy dissipation in optical dielectric coatings
摘要：
近年来，越来越多的设备和实验表明，机械热噪声的限制。特别是亚赫兹激光频率稳定和引力波探测器，能够测量1 E-18 m/rtHz或更小的波动，受到沉积在反射镜上的电介质涂层中的热噪声的限制。本文提出了一种测量微悬臂梁上低吸收介质膜热噪声的新方法，并与机械损耗测量结果进行了比较。涂层热噪声是在最宽的频率范围内测量的，具有有史以来最高的信噪比。此外，我们提出了一种新的技术来推断涂层的机械损耗的机械品质因数的测量，它不依赖于知识的涂层和基板的杨氏模量。电介质涂层是通过离子束溅射沉积的。本文给出的结果给出了（4.70 $\pm$ 0.2）× 1 E-4的与频率无关的损耗角，退火钽从10 Hz到20 kHz的杨氏模量为118 GPa。对于沉积态二氧化硅，在该频率范围内观察到弱的频率依赖性（~ f^{-0.025}），在16 kHz下杨氏模量为70 GPa，内阻尼为（6.0 $\pm$ 0.3）× 1 E-4，但该值在退火后减小一个数量级，并且频率依赖性消失。
英文摘要：
In recent years an increasing number of devices and experiments are shown to be limited by mechanical thermal noise. In particular sub-Hertz laser frequency stabilization and gravitational wave detectors, that are able to measure fluctuations of 1E-18 m/rtHz or less, are being limited by thermal noise in the dielectric coatings deposited on mirrors. In this paper we present a new measurement of thermal noise in low absorption dielectric coatings deposited on micro-cantilevers and we compare it with the results obtained from the mechanical loss measurements. The coating thermal noise is measured on the widest range of frequencies with the highest signal to noise ratio ever achieved. In addition we present a novel technique to deduce the coating mechanical losses from the measurement of the mechanical quality factor which does not rely on the knowledge of the coating and substrate Young moduli. The dielectric coatings are deposited by ion beam sputtering. The results presented here give a frequency independent loss angle of (4.70 $\pm$ 0.2)x1E-4 with a Young's modulus of 118 GPa for annealed tantala from 10 Hz to 20 kHz. For as-deposited silica, a weak frequency dependence (~ f^{-0.025}) is observed in this frequency range, with a Young's modulus of 70 GPa and an internal damping of (6.0 $\pm$ 0.3)x1E-4 at 16 kHz, but this value decreases by one order of magnitude after annealing and the frequency dependence disappears.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
