Development of a Variable Bandwidth Laser Interferometer Gravitational Wave Antenna

有几个项目正在进行中，目标是使用激光干涉仪探测引力波：日本的TAMA项目，美国的LIGO项目，法国-意大利的处女座项目，以及德国-英国的GEO项目。引力波很有可能在几年内被探测到。但要建立引力波天文学，必须进一步提高天线的灵敏度。共振边带提取(RSE)是一种可变带宽干涉仪，是在有限频段内提高干涉仪灵敏度的先进技术之一。到目前为止，关于RSE干涉仪已经进行了几次基本实验，但都是在空气中进行的台式实验，而且都是采用多调制方案进行信号提取。由于RSE干涉仪对臂腔的精细度要求极高，因此MIRR…的反射率极高另外，干涉仪不宜在空气中操作，因为空气中的反射镜可能会退化。此外，桌面实验使用的是固定在桌子上的镜子，这与真正的引力波灯笼中的悬浮镜子非常不同。此外，多调制方案使得干涉仪的控制更加复杂，因此在本研究中，我们使用了一个小的悬浮系统在真空系统中进行了实验，这使得我们有可能有一个更好的、更逼真的环境。我们还发明了一种信号提取的单一调制方法，保证了控制系统的简单性。我们在世界上首次成功地在悬挂镜真空系统中实现了一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适用于小悬架系统的感应电流减振方法。除了上述成功之外，我们还一直在研究在桌面实验中使用偏振方法的可能性。在RSE干涉仪的理论方面，我们一直在对干涉仪的量子噪声进行分析，经过努力和成功，我们相信只要通过进一步的实验优化设计参数，就可以完成未来大型天线的RSE干涉仪的设计。较少

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