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在诸如激光冷却原子、光频标和冷原子干涉等实验中,通常采用压控振荡器(VCO)技术对激光移频,但是移频精度和稳定性不能满足实验要求。本文提出并研制了一种直接数字频率合成器(DDS)及其专用高精度时序控制系统用于激光的移频。DDS基于AD9852芯片,配合微控制器(MCU)控制其参数,输出经功率放大后直接驱动声光调制器以调控激光频率。上位计算机端的专用控制系统采用Labview平台结合高精度数据采集卡,以精确地调控时序。经测试,系统产生的信号相噪低、线宽窄于5Hz、谐波抑制比优于30dB、频率精度优于10-7和时序调控精度优于1μs,且参数调节方便、控制界面友好,这一系统已成功地应用在激光冷却原子和原子喷泉实验中。
In experiments such as laser cooling of atoms, optical frequency standard and cold atomic interference, VCOs are usually used to shift the laser frequency, but the accuracy and stability of the frequency shift can not meet the experimental requirements. This paper presents and develops a direct digital frequency synthesizer (DDS) and its dedicated high-precision timing control system for laser frequency shift. DDS based on AD9852 chip, with the microcontroller (MCU) to control its parameters, the output power amplifier directly drives the acousto-optic modulator to control the laser frequency. Host computer-specific control system using Labview platform with high-precision data acquisition card to accurately control the timing. Tested, the system produces low phase noise, line width is less than 5Hz, harmonic rejection better than 30dB, frequency accuracy is better than 10-7 and timing control accuracy better than 1μs, and easy parameter adjustment, the control interface is friendly, this The system has been successfully used in laser cooling atomic and atomic fountain experiments.