DETECTION OF MAGNETO-OPTIC EFFECT OF THE VACUUM-HIGH-SENSITIVITY POLARIZATION SPECTROSCOPY

研究了用高灵敏度偏振光谱检测真空磁光效应的方法。1)用于检测真空中产生的超小双折射。利用光学腔增强偏振信号。我们提出了一种偏振检测系统，其中一个腔具有两个功能：信号增强和锁定激光频率。利用该系统和低精密度腔，我们获得了法拉第效应测量的32倍信号增强。同时，我们构建了一个高精细度的腔体（F= 6 × 10^4），并利用偏振相关腔环衰法研究了腔体反射镜的光学各向异性。提出了通过优化反射镜光轴来减小各向异性的方法。2)开发了单通道极化信号的高灵敏度检测方法。为了降低背景噪声，我们将偏振分析仪系统的消光比提高到10^<-10>，从而使光源强度波动引起的噪声降低到射孔噪声以下的水平。可以检测到椭圆度变化的最小值为10^<-10> rad，可以检测到具有最小磁致双折射值的He气体的非共振Voigt效应。本文的研究结果对开发用于检测真空磁光效应的偏振光谱系统具有一定的指导意义

We investigated high-sensitivity polarization spectroscopy for detection of the magneto-optic effect of the vacuum.1) For detection of the ultra-small birefringence induced in the vacuum. Optical cavities are used to enhance the polarization signal. We proposed a polarization detection system in which a single cavity served two functions : signal enhancement and locking of a laser frequency. Using this system with a low finesse cavity we obtained the ' signal enhancement of 32 for the Faraday effect measurement. Meanwhile, we constructed a high-finesse cavity (F= 6 x 10^4 ), and investigated the optical anisotroy of the cavity mirrors using the polarization dependence cavity ring down method. We presented to minimize the anisotropy by optimization of the optical axes of the mirrors.2) We developed the high-sensitivity detection of the polarization signal for a single-pass arrangement. In order to reduce background noise we improved the extinction ratio of the polarization analyzer system to 10^<-10> so that the noise caused by intensity fluctuation of the light source was reduced to a level below that of shot noise. The minimum value that could be detected for the ellipticity change was 10^<-10> rad. We could detect the off-resonant Voigt effect of He gas that had the smallest value of the magnetically induced birefringence.The results thus obtained in the present study are useful for development of the polarization spectroscopic system to detect the magneto-optic effect of the vacuum