532 nm碘分子光频标

建立了两套可搬运型碘分子稳频的532 nm固体激光频标装置,其中一套采用了自行研制的半非平面单块固体环形激光器作为光源,在该激光器中采用密封隔离罩消除了气压抖动造成的影响。在两套装置中,利用折叠光路实现了4倍碘室长度的1.8 m的实际光学吸收程,大大提高了误差信号的信噪比。设计并建立了主动温度反馈控制系统,有效抑制了电光相位调制器中剩余幅度调制的变化。两套系统频率同时锁定在碘分子的超精细谱线R(56)32-0的a10分量上。连续不间断15×104s的拍频测量结果表明:1 s采样时间的激光频率稳定度的Allan方差优于2.4×10-14,大于200 s采样时间的激光频率稳定度的最小Allan方差典型值可达到4×10-15。

532 nm Iodine Molecular Optical Frequency Standards

Two portable 532 nm optical frequency standards stabilized at iodine molecular are established. A home-made semi-nonplanar monolithic laser is used as one of the laser source. A sealed box is adopted in the laser to suppress the dither produced by the atmosphere pressure. The 1.8-m absorption length is obtained by using a 4-pass strategy in a 45-cm iodine cell, which increases signal-to-noise radio greatly, and the fluctuations of the residual amplitude modulations are suppressed by an active servo feedback control of the crystal temperature in an electro-optic modulator. The laser frequency stability was measured. Frequencies of the two systems are simulataneously stabilized at a10 component of the R(56)32-0 spectral line of iodine molecular. The square root Allan variance has achieved better than 2.4×10-14 for 1-s averaging time and 4×10-15 on the flicker floor. The same Allan variance for 10000 s averaging time has been reached during a continuous 15×104 s measuring period.