Thermal noise reduction and absorption optimization via multimaterial coatings
Thermal noise reduction and absorption optimization via multimaterial coatings
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通过多材料涂层降低热噪声并优化吸收
DOI：
10.1103/physrevd.91.042001
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发表时间：
2014
影响因子：
5
通讯作者：
R. Schnabel
中科院分区：
文献类型：
--
作者：
J. Steinlechner;I. Martin;J. Hough;C. Krueger;S. Rowan;R. Schnabel
未来的重力波探测器（GWD），例如高级Ligo升级和爱因斯坦望远镜，计划在低温温度下使用晶硅（CSI）测试物镜在低温温度下以1550 nm的降低提供直接的操作波长。减少涂层的热噪声，但目前使用的涂层堆栈由二氧化硅（Sio2）和Tantala（TA2O5）组成，显示出低温噪声峰值，这会导致较低的热噪声。硅（ASI）是饮食镜涂层的非常有希望的候选材料，不幸的是，由于ASI涂层中的高光吸收，这种ASI/SIO2涂层不适用于GWD。基于材料的涂层在这种多材料设计中。在最外面的涂层中，低吸收的TA2O5显着降低了入射光功率，而ASI仅在下部双层中使用，以维持低光的光学吸收。热噪声占25％。
Future gravitational wave detectors (GWDs) such as Advanced LIGO upgrades and the Einstein Telescope are planned to operate at cryogenic temperatures using crystalline silicon (cSi) test-mass mirrors at an operation wavelength of 1550 nm. The reduction in temperature in principle provides a direct reduction in coating thermal noise, but the presently used coating stacks which are composed of silica (SiO2) and tantala (Ta2O5) show cryogenic loss peaks which results in less thermal noise improvement than might be expected. Due to low mechanical loss at low temperature amorphous silicon (aSi) is a very promising candidate material for dielectric mirror coatings and could replace Ta2O5. Unfortunately, such an aSi/SiO2 coating is not suitable for use in GWDs due to high optical absorption in aSi coatings. We explore the use of a three material based coating stack. In this multimaterial design the low absorbing Ta2O5 in the outermost coating layers significantly reduces the incident light power, while aSi is used only in the lower bilayers to maintain low optical absorption. Such a coating design would enable a reduction of Brownian thermal noise by 25%. We show experimentally that an optical absorption of only (5.3±0.4) ppm at 1550 nm should be achievable.