高精细度光学参考腔的自主化研制  

Self-reliance and independently developed high-finesse spherical ultrastable optical reference cavity

作　　者：刘军[1,2] 陈帛雄[3] 许冠军[2] 崔晓旭[3] 白波[3] 张林波[2] 陈龙[2] 焦东东[2] 王涛[3] 刘涛[2] 董瑞芳[2] 张首刚[2] 

机构地区：[1]中国科学院大学,北京100049 [2]中国科学院国家授时中心时间频率基准实验室,西安710600 [3]中航工业西安飞行自动控制研究所,西安710065

出　　处：《物理学报》2017年第8期14-23,共10页Acta Physica Sinica

基　　金：国家重大科研仪器设备研制专项(批准号:61127901);国家自然科学基金(批准号:11273024;61025023);国家自然科学基金青年科学基金(批准号:11403031)资助的课题~~

摘　　要：高精细度超稳光学参考腔是获得超窄线宽激光的核心部件.本文报道了面向空间应用的高精细度球形超稳光学参考腔自主化研制及其初步测试结果.设计球形腔体直径为80 mm,腔长78 mm,采用平-凹腔镜结构,凹镜曲率半径为0.5 m.使用有限元方法计算了该参考腔的震动敏感度,最佳支撑位置的震动敏感度小于1×10^(-10)/g.采用超光滑表面三级抛光技术实现光学表面粗糙度小于0.4 nm(rms)的超精密加工,采用双离子束溅射法实现工作波长反射率大于99.999%、损耗小于4 ppm腔镜镀膜,干式光胶方法键合腔体和腔镜.利用扫腔线宽法和腔衰荡法对参考腔的线宽和精细度进行了测量,结果表明该参考腔的精细度约为195000,线宽为9.8 kHz.将698 nm半导体激光器锁定到该参考腔上测得其损耗<5 ppm.与实验室进口同类型参考腔相比较,主要性能指标与其相当.Ultra-stable reference cavity with high finesse is a crucial component in a narrow-linewidth laser system which is widely used in time and frequency metrology,the test of Lorentz invariance,and measure of gravitational wave.In this paper,we report the recent progress of the self-made spherical reference cavity,aiming at the future space application.The main function of cavity is the reference of ultra-stable laser,which is the local reference oscillation source of space optical clock.The diameter of the designed spherical cavity spacer made of ultra-low expansion glass is 80 mm,and the cavity length is 78 mm,flat-concave mirrors configuration,and the radius of the concave mirror is 0.5 m.The support structure is designed to have two 3.9 mm-radius spherical groves located at the poles of the sphere along the diameter direction（denned as support axis）,and a 53 angle between the support axis and the optical axis.The mechanic vibration sensitivities of the cavity along and perpendicular to the optical axis are both calculated by finite element analysis method to be below 1 × 10^-10/g.Five-axis linkage CNC machining sphere forming technology is applied to SΦ80 mm spherical surface processing with spherical contour degree up to 0.02.After a three-stage surface polishing processes,the fused silicamirror substratessurface roughness is measured to be less than 0.2 nm（rms）.Implementing double ion beam sputtering technique for mirror coating,the reflection of the coating achieves a reflectivity of 〉99.999%and a loss of 4 ppm for 698 nm laser.The coating surface roughness is measured to be〈 0.3 nm（rms）.The cavity spacer and the mirror are bonded by dried optical contact.In order to improve the thermal noise characteristics of the cavity,an ultra low expansion ring is contacted optically to the outer surface of the mirror.The cavity is characterized by ring-down spectroscopy,and the finesse is around 195000.With the help of a homemade 698 nm ultra narrow line-width laser,the cavity line-width is measured to

关 键 词：超稳腔 超低膨胀系数 精细度 光钟 

分 类 号：TN24[电子电信—物理电子学]