标题： 晶体硅的双折射测量 显示英文标题

标题： Birefringence Measurements on Crystalline Silicon

摘要： 晶体硅已被提议作为第三代引力波探测器（如爱因斯坦望远镜（ET））的新测试质量材料。 双折射会降低干涉仪的对比度，并在干涉仪中产生动态扰动。 在这项工作中，我们使用了包含硅作为双折射介质的法布里-珀罗腔的偏振依赖共振频率分析方法。 我们的测量结果显示，在激光波长为1550nm和室温下，沿（111）轴的硅双折射约为$\Delta\, n \approx 10^{-7}$。 提出了一种模型，解释了我们不同测量设置的结果，该模型将外部应力引起的弹性应变和可能在生产过程中产生的塑性应变的叠加考虑在内。 将我们的理论应用于所提出的ET测试质量几何结构，表明由于弹性应变导致的双折射没有关键影响。 显示英文摘要

摘要： Crystalline silicon has been proposed as a new test mass material in third generation gravitational wave detectors such as the Einstein Telescope (ET). Birefringence can reduce the interferometric contrast and can produce dynamical disturbances in interferometers. In this work we use the method of polarisation-dependent resonance frequency analysis of Fabry-Perot-cavities containing silicon as a birefringent medium. Our measurements show a birefringence of silicon along the (111) axis of the order of $\Delta\, n \approx 10^{-7}$ at a laser wavelength of 1550nm and room temperature. A model is presented that explains the results of different settings of our measurements as a superposition of elastic strains caused by external stresses in the sample and plastic strains possibly generated during the production process. An application of our theory on the proposed ET test mass geometry suggests no critical effect on birefringence due to elastic strains.