面向TDI技术地面验证的激光干涉仪本底噪声分析

Background noise analysis of laser interferometer for test of TDI technology on ground

在空间引力波探测中,由于星间激光干涉臂不等,导致激光频率噪声不能共模消除,从而使微弱的引力波信号被激光频率噪声淹没。时间延迟干涉(TDI)技术通过将激光相位数据在时间上延迟,构成虚拟等臂干涉,从而能减小激光频率噪声对引力波信号探测的影响。为了在地面验证TDI技术能够将激光频率噪声对引力波探测的影响降低至3×10^(-7) Hz/√Hz(傅里叶频率1 mHz处),需要分析TDI地面验证系统本底噪声的主要来源。通过实验测量和计算分析,提出了面向TDI技术地面验证的激光干涉仪的重要参数设计要求,包括激光干涉臂的臂长差、激光频率稳定度、气压稳定度、激光功率稳定度以及各部件温度稳定度等。

For space gravitational wave detection,as the lengths of laser interferometer arms are not matched,the laser frequency noise cannot be eliminated in common mode,leading to the weak interfering signals being submerged in large residual laser frequency noise.By time-shifting and linearly combining independent interfering signals,laser frequency noise can be greatly eliminated as laser interferometry with virtual equal interferometer arm lengths.Such a technique is called time delay interferometry(TDI).In order to experimentally validate that TDI technique can reduce the influence of laser frequency noise on gravitational wave detection to 3×10^(-7) Hz/√Hz at Fourier frequency of 1 mHz on the ground,it is necessary to analyze the main frequency noise sources of laser interferometer.Based on experimental measurement and calculation analysis,experimental parameters of the laser interferometer are derived to meet the noise requirement of gravitational wave detection,including the maximum length difference between interferometer arms,laser frequency stability,air pressure stability,laser power stability and temperature stability of experimental setups.