Development of a Variable Bandwidth Laser Interferometer Gravitational Wave Antenna

有几个项目正在进行中，旨在使用激光干涉仪进行引力波探测：日本的TAMA项目，美国的LIGO项目，法国-意大利的VIRGO项目和德国-英国的GEO项目。引力波很有可能在几年内被探测到。然而，为了建立引力波天文学，还需要进一步提高天线的灵敏度，共振边带提取（RSE）干涉仪是一种变带宽干涉仪，是在有限频带内提高干涉仪灵敏度的先进技术之一，目前已经进行了几次基本的实验研究。但它们都是在空中进行的桌面实验，而且它们都使用多调制方案来提取信号。由于RSE干涉仪要求臂腔具有极高的精细度，因此需要极高的镜反射率。 ...更多信息 或者，由于反射镜在空气中可能退化，在空气中操作干涉仪不是优选的。此外，桌面实验使用固定在桌子上的镜子，这与真实的引力波天线中悬挂的镜子非常不同。此外，多重调制方案使得干涉仪的控制更加复杂，因此在本研究中，我们使用小型悬浮系统在真空系统中进行实验，这使得有可能获得更好和更真实的环境。在信号提取方面，我们还提出了一种单一的调制方式，保证了控制系统的简单性。我们在世界上首次成功地在悬镜真空系统中实现了单次调制三次谐波解调的RSE干涉仪。我们还成功地开发了一种用于小型悬挂系统的感应电流阻尼方法。除了上述成功，我们一直在研究在桌面实验中使用偏振方法的可能性。在RSE干涉仪的理论研究方面，我们对干涉仪的量子噪声进行了理论分析，通过进一步的实验优化设计参数，我们相信可以完成未来大天线RSE干涉仪的设计。少

There are several projects going on, which aim at gravitational wave detection using laser interferometers : the Japanese TAMA project, the American LIGO project, the French-Italian VIRGO project, and the German-British GEO project. It is quite possible that gravitational waves could be detected in several years. However, it is necessary to improve the sensitivity of the antennas further in order to establish the gravitational wave astronomy.The resonant sideband extraction (RSE), which is a variable bandwidth interferometer, is one of the advanced technologies that could improve the sensitivity of the interferometer in a limited frequency band.There has been several basic experiments on the RSE interferometer so far, but they were all performed as table-top experiments in the air, as well as they were all using multi-modulation schemes for signal extraction. Since the RSE interferometer requires an extremely high finesse of the arm cavity, thus, extremely high reflectivity of the mirr … More ors, it is not preferable to operate the interferometer in the air because of possible degradation of the mirrors in the air. Also the table-top experiment uses mirrors fixed to the table, which are very different from the suspended mirrors in a real gravitational wave lantenna. Moreover, the multi-modulation scheme makes the interferometer control even more complicated.Therefore in this research, we performed the experiment in the vacuum system using a small suspension system, which made it possible to have a better and more realistic environment. Also we invented a single modulation method for signal extraction, which ensures the simplicity of the control system. We have succeeded in operating the RSE interferometer using the single modulation with the third harmonic demodulation in a vacuum system using suspended mirrors for the first time in the world. We also successfully developed an induced current damping method for the small suspension system. Other than the above-mentioned success, we have been investigating the possibility of using a polarization method in a table-top experiment. In the theoretical aspect of the RSE interferometer, we have been analizing the quantum noise of the interferometer.With all the efforts and success altogether we believe that we will be ready to finalize the design of the RSE interferometer for the future large antenna just by optimizing the design parameters by further experiment. Less