用于原子重力仪的扫频频率源系统

原子重力测量实验中，需要通过扫频频率源来实现主从Raman激光的线性啁啾，进而补偿原子在自由下落过程中产生的多普勒频移，实现当地重力加速度g的测量。针对传统扫频频率源体积大、发热量大的问题，通过AD9959数字芯片设计了一款扫频频率源，可用作原子喷泉扫频控制和Raman光锁相环鉴频鉴相本振参考。最终通过实验测得：该扫频信号源的相位噪声为-112 dB@1 kHz，频率稳定度为1.38×10^-11@1 s，对原子重力仪灵敏度影响为2.81×10^-9 g/Hz^1/2，600 s积分时间对原子重力仪实验影响为1.15×10^-10 g。该系统具有低噪声、高稳定度的特点，可满足搬运式原子重力仪分辨力10^-10 g需求。研究结果为原子重力仪从原理样机向工程化可搬运实验测试仪器发展提供了一定参考。

Swept frequency source system for atomic gravimeter

In the atomic gravity measurement experiments, the linear chirp of the master and slave Raman lasers is achieved by a swept frequency source, which in turn compensates for the Doppler frequency shift produced by the atoms during free fall, thus enabling the measurement of the local gravitational acceleration g. Aiming at the problems of large volume and large heat generation of the traditional sweptfrequency source, this paper uses the AD9959 digital chip to implement a swept frequency source, which can be used as an atomic fountain frequency sweeping control and Raman optical phase-locked loop discriminating frequency and phase local oscillation reference. The final experiment shows that the phase noise of the swept frequency source is -112 dB@1 kHz, and the frequency stability is 1.38×10^-11@1 s. The effect on the sensitivity of the atom gravimeter is 2.81×10^-9 g/Hz^1/2, and the effect on the atomic gravimeter experiment is 1.15×10^-10 g within 600 s integration time. The system has the characteristics of low noise and high stability, and can meet the 10^-10 g resolution requirement of portable atomic gravimeter. The research results provide a certain reference for the development of atomic gravimeter from the principle prototype to the engineering portable experimental test instrument.