Luo Qin, Zhang Heng, Zhang Ke, Duan Xiao-Chun, Hu Zhong-Kun, Chen Le-Le, Zhou Min-Kang
MOE Key Laboratory of Fundamental Physical Quantities Measurements, Hubei Key Laboratory of Gravitation and Quantum physics, School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.
Rev Sci Instrum. 2019 Apr;90(4):043104. doi: 10.1063/1.5053132.
A compact laser system for a portable Rb atom interferometry gravimeter has been demonstrated in this work. This laser system is based on frequency doubling of a single seed laser at the wavelength of 1560 nm. The frequency of the seed laser is controlled by a digital unit with an analog feedback circuit. By using this frequency control method, the frequency of the laser system can be shifted over 1 GHz. Based on this method, the Raman frequency can be locked on the F = 3 → F' = 4 transition of Rb atoms. Moreover, the Raman sideband and the repumping laser are generated by a phase modulator, and it can generate different laser frequencies to meet the requirements of a typical atom interferometer. Additional sidebands in the Raman beam produced from the phase modulator are optimized and reduced, allowing us to observe atom interference with a free evolution time of 320 ms. The control unit including the laser system has been integrated into a box with a volume of 1.5 m × 0.6 m × 0.6 m, and the weight of which is only 150 kg. Using this compact optical scheme, our atomic gravimeter has achieved a sensitivity of 53 μGal/Hz and a resolution of better than 1 μGal (1 μGal = 1 × 10 m/s) in an integration time of 3000 s.
在这项工作中展示了一种用于便携式铷原子干涉重力仪的紧凑型激光系统。该激光系统基于波长为1560 nm的单种子激光的倍频。种子激光的频率由带有模拟反馈电路的数字单元控制。通过使用这种频率控制方法，激光系统的频率可以在1 GHz以上进行偏移。基于此方法，拉曼频率可以锁定在铷原子的F = 3→F' = 4跃迁上。此外，拉曼边带和再泵浦激光由相位调制器产生，并且它可以产生不同的激光频率以满足典型原子干涉仪的要求。对相位调制器产生的拉曼光束中的附加边带进行了优化和降低，使我们能够观察到自由演化时间为320 ms的原子干涉。包括激光系统在内的控制单元已集成到一个体积为1.5 m×0.6 m×0.6 m的盒子中，其重量仅为150 kg。使用这种紧凑的光学方案，我们的原子重力仪在3000 s的积分时间内实现了53 μGal/Hz的灵敏度和优于1 μGal（1 μGal = 1×10 m/s）的分辨率。
