Abstract
光束在行經強磁場作用下的真空中, 若此入射光束為線性偏極光且其偏極方向與外加磁場方向呈 45度, 因量子電動力學效應, 在平行磁場的分量產生相位延遲, 因而造成橢圓偏振, 此種現象稱為量子電動力學的真空雙折射。另外, 為了滿足在強作用力下不違反 CP變換的不變性, 引進軸粒子 (Axion) 理論, 軸粒子與光子之間的作用會有軸粒子的生成及幻滅的現象, 造成入射偏振光被延遲或吸收, 因而產生雙折射現象及偏振方向的旋轉。藉由量度強磁場作用下, 真空中光束的雙折射現象及偏振方向的旋轉,可驗證 QED 理 論及軸粒子的存在與否。本篇論文乃針對這項研究做了初步的準備工作。 因 QED 效應及軸粒子引起的雙折射現象極小, 量測的精密度要求極高, 對於所使用的雷射光源在頻率穩定度的要求相對地非常嚴格, 故第一步工作即對所採用的 Nd:YAG (1064 nm)雷射做穩頻控制。 本篇論文根據 Pound-Drever 穩頻架構, 分析其原理, 設計穩頻回饋控制的電子線路, 完成穩頻工作, 將 Nd:YAG 雷射鎖在長123cm, 精度 (Finesse) 高達 15,000 的 Fabry-Perot 共振腔, 並在實驗過程中觀察雷射光在長生命期 (Photon Life time), 高精度的共振腔下由入射光與共振腔內光場因干涉而生的瞬時變化現象。When propagating perpendicular to a strong magnetic field,light is predicted slowing down. The index is dependent on thepolarization of the light. This prediction is based on thetheory of quantum electrody namics (QED) which treats thevacuum as a sea of virtual particle pairs. A deviation fromthe expected result would indicates the existence of a class ofspin 0 particles that can couple to two photons. An example ofsuch particle is an axion responsible for breaking of theglobal symmetry and introduced to explain the absence of the CPviolation in strong interaction. This particle could causebirefrigence and polarization of light. For the test of QED andserach for light scalar/pseudoscalar particles using ultra-highsensitive interferometers, the first step is to have a highstablized light source to detect the extremely small effect.In this paper, using Pound-Drever scheme we stablize Nd:YAGlaser on a Fabry-Perot interferometer with a finesse of 15,000and a length of 123 cm. We have established the electronicfeedback control circuit and observed some interestinginstantaneous phenomenon according to the long photon life timein the cavity.