建立了两套可搬运型碘分子稳频的532nm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1.8m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α10分量上。连续不间断15×10^4s的拍频测量结果表明:1s采样时间的激光频率稳定度的Allan方差优于2.4×10^-14,大于200s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。
Two portable 532 nm optical frequency standards stabilized at iodine molecular are established. A homemade 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 electrooptic modulator. The laser frequency stability was measured. Frequencies of the two systems are simulataneously stabilized at α10 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 ×10^-4 s measuring period.