Mirror thermal noise is and will remain one of the main limitations to the sensitivity of gravitational wave detectors based on laser interferometers. We report about projected mirror thermal noise due to losses in the mirror coatings and substrates. The evaluation includes all kind of thermal noises presently known. Several of the envisaged substrate and coating materials are considered. The results for mirrors operated at room temperature and at cryogenic temperature are reported.
Cryogenic mirrors have been introduced to the KAGRA gravitational wave telescope in Japan, and are also planned to be used in next-generation gravitational wave telescopes to further improve their sensitivity. Molecular gases inside vacuum chambers adhere to cold mirror surfaces because they lose their kinetic energy when they hit cryogenic surfaces. Finally, a number of adsorbed molecules form an adlayer, which will grow with time. The growing adlayer functions as an optical coating and changes the properties of the underlying mirror, such as reflectance, transmittance, and absorption, which …
Thermoelastic-damping noise from sapphire mirrors in a fundamental-noise-limited interferometer
我们报告的第一个高精度干涉仪使用大蓝宝石镜，我们提出了第一个直接的，宽带测量的基本热噪声在这些镜子。我们的研究结果与Braginsky等人的热弹性阻尼噪声预测吻合得很好。A 264，1（1999）]和Cerdonio等人[Phys. Rev. D 63，082003（2001）]，它们已被用于预测先进干涉引力波探测器的天体物理范围。
Enhancing of sensitivity of the opto-acoustical gravitational wave (GW) antenna OGRAN installed in the underground facilities of Baksan Neutrino Observatory is analyzed. Calculations are presented showing a sensitivity improving on two orders of value after a cooling the solid body acoustical part of the antenna to the nitrogen temperature. A possibility of keeping of the same optical scheme of the antenna at low temperature is discussed. Design of modernized construction for cryogenic version of the antenna OGRAN is described. Test experiments with cooled pilot model carrying cryogenic mirror…
The implications of Mexican-hat mirrors: calculations of thermoelastic noise and interferometer sensitivity to perturbation for the Mexican-hat-mirror proposal for advanced LIGO
我们测量了在音频（5 Hz - 4 kHz）的单一交叉偏振干涉仪的光热效应。在法布里-珀罗干涉仪中，一个偏振方向的光被截断以周期性地加热干涉仪反射镜，而正交偏振方向的光测量反射镜长度的变化。抛光固体金属镜的测试显示出与Braginsky等人[“Thermodynamical fluctuations and photo-thermal散粒噪声in引力波antennas，”Physics Letters A 264，1-10（1999）]和Cerdonio等人[“Thermoelastic effects at low temperatures and quantum limits in displacement measurement，“Physical Review D 63 082003（2001）]描述了未涂覆的光学器件。
The sensitivity of kilometer-scale terrestrial gravitational wave interferometers is limited by mirror coating thermal noise. We explore the effect of folding the arm cavities of such interferometers. While simple folding alone does not reduce the mirror coating thermal noise, it makes the folding mirror the critical mirror, opening up a variety of design and upgrade options.
We compare a conventional Mach-Zehnder light-pulse atom interferometer based on diffractive mirrors with one that uses specular reflection. In contrast to diffractive mirrors that generate a symmetric configuration, specular mirrors realized, for example, by evanescent fields lead under the influence of gravity to an asymmetric geometry. In such an arrangement the interferometer phase contains nonrelativistic signatures of proper time.
Cryogenic Mechanical Loss of GaAs/AlGaAs Crystalline Coatings
Syracuse University（雪城大学）；Cardiff University（卡迪夫大学）；Hobart William Smith Colleges（霍巴特威廉史密斯学院）；California Institute of Technology（加州理工学院）；University of Arizona（亚利桑那大学）
For further gravitational wave (GW) detections, it is significant to invent a technique to reduce all kinds of mirror displacement noise dominant at low frequencies for ground-based detectors. The neutron displacement-noise-free interferometer (DFI) is one of the tools to reduce all the mirror displacement noise at lower frequencies. In this paper, we describe a further simplified configuration of a neutron DFI in terms of neutron incidence direction. In the new configuration, neutrons enter the interferometer with unidirectional incidence at four speeds as opposed to two bidirectional inciden…
The improvement of sensitivity to gravitational waves (GWs) at lower frequencies is still challenging on account of displacement noise. One of the solutions is the neutron displacement-noise-free interferometer (DFI). We focus on a simplification of the detector configuration by taking advantage of the ability to adjust the neutron speed depending on the configuration. The new configuration consists of two beamsplitters and two mirrors, which constitute a single Mach-Zehnder interferometer (MZI). It is simpler than the configuration with two MZIs in previous research. All displacement noise of…
Cryogenic measurement of the optical absorption coefficient in sapphire crystals at 1.064(micro)m for the Large-scale Cryogenic Gravitational wave Telescope
KAGRA is a 3-km cryogenic interferometric gravitational wave telescope located at an underground site in Japan. In order to achieve its target sensitivity, the relative positions of the mirrors of the interferometer must be finely adjusted with attached actuators. We have developed a model to simulate the length control loops of the KAGRA interferometer with realistic suspension responses and various noises for mirror actuation. Using our model, we have designed the actuation parameters to have sufficient force range to acquire lock as well as to control all the length degrees of freedom witho…
Instrumental development for Cryogenic sub-Hz cROss torsion bar detector with quantum NOn-demolition Speed meter (CHRONOS)
Institute of Physics, Academia Sinica（中央研究院物理研究所）；Center for High Energy and High Field Physics (CHiP), National Central University（国立中央大学高能高场物理中心）；Department of Physics, National Central University（国立中央大学物理系）；Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK)（高能加速器研究机构粒子与核研究部）；National Institute of Physics, University of the Philippines - Diliman（菲律宾大学迪利曼分校国家物理研究所）
As part of the upgrade program of the Advanced Virgo interferometer, the installation of new instrumented baffles surrounding the main test masses is foreseen. As a demonstrator, and to validate the technology, the existing baffle in the area of the input mode cleaner end-mirror will be first replaced by a baffle equipped with photodiodes. This paper presents detailed simulations of the light distribution on the input mode cleaner baffle, with the aim to determine the light exposure of the photodiodes under different scenarios of the interferometer operation.
Science of Cryogenic sub-Hz cROss torsion bar detector with quantum NOn-demolition Speed meter (CHRONOS)
National Central University（中央大学）；Center for High Energy and High Field (CHiP), National Central University（国立中央大学高能高场中心）；Institute of Physics, Academia Sinica（中央研究院物理研究所）；Institute of Particle and Nuclear Studies, High Energy Acceleration Research Organization (KEK)（高能加速器研究机构粒子核研究部）；National Institute of Physics, University of the Philippines - Diliman（菲律宾大学迪利曼分校国家物理研究所）
Fundamental sensitivity of an optical interferometric gravitational wave detector increases with increase of the optical power which, in turn, limited because of the opto-mechanical parametric instabilities of the interferometer. We propose to optimize geometrical shape of the mirrors of the detector to reduce the diffraction-limited finesse of unessential optical modes of the interferometer resulting in increase of the threshold of the opto-mechanical instabilities and subsequent increase of the measurement sensitivity. Utilizing parameters of the LIGO interferometer we found that the propose…
The detection of gravitational waves from compact binary mergers by LIGO has opened the era of gravitational wave astronomy, revealing a previously hidden side of the cosmos. To maximize the reach of the existing LIGO observatory facilities, we have designed a new instrument that will have 5 times the range of Advanced LIGO, or greater than 100 times the event rate. Observations with this new instrument will make possible dramatic steps toward understanding the physics of the nearby universe, as well as observing the universe out to cosmological distances by the detection of binary black hole …
Mirror Surface Evaluation for the Einstein Telescope Using Virtual Mirror Maps
Vrije Universiteit Amsterdam（阿姆斯特丹自由大学）；Nikhef, National Institute for Subatomic Physics（荷兰亚原子物理国家研究所）；Maastricht University（马斯特里赫特大学）；Delft University of Technology (TU Delft)（代尔夫特理工大学）；Laboratoire des Matériaux Avancés (LMA), Université de Lyon, CNRS/IN2P3（里昂大学先进材料实验室）
KAGRA is a 3-km interferometric gravitational wave telescope located in the Kamioka mine in Japan. It is the first km-class gravitational wave telescope constructed underground to reduce seismic noise, and the first km-class telescope to use cryogenic cooling of test masses to reduce thermal noise. The construction of the infrastructure to house the interferometer in the tunnel, and the initial phase operation of the interferometer with a simple 3-km Michelson configuration have been completed. The first cryogenic operation is expected in 2018, and the observing runs with a full interferometer…
The sensitivity of current and planned gravitational wave interferometric detectors is limited, in the most critical frequency region around 100 Hz, by a combination of quantum noise and thermal noise. The latter is dominated by Brownian noise: thermal motion originating from the elastic energy dissipation in the dielectric coatings used in the interferometer mirrors. The energy dissipation is a material property characterized by the mechanical loss angle. We have identified mixtures of titanium dioxide (TiO$_2$) and germanium dioxide (GeO$_2$) that show internal dissipations at a level of 1 $…
