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中国物理学会期刊

面向空间引力波探测的程控低噪声高精度电压基准源

CSTR: 32037.14.aps.72.20222119

Programmable precision voltage reference source for space-based gravitational wave detection

CSTR: 32037.14.aps.72.20222119
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  • 引力波探测打开了探索宇宙的新窗口, 开启了多信使天文学时代. 大型激光干涉仪作为空间及地基引力波探测装置, 需要使用低噪声激光光源, 通过光电负反馈降噪技术可以抑制激光噪声, 提高大型激光干涉仪的灵敏度. 光电负反馈控制需要将光电探测器信号与电压基准源信号相减, 之后经过比例积分微分器得到误差信号, 来控制泵浦电流驱动器的输出功率, 从而实现激光噪声抑制. 由于光电探测器信号受激光强度影响, 其输出电压在一定范围内变化, 这就需要电压基准源信号的输出电压可变; 另外, 电压基准源的性能直接影响反馈控制环路的整体性能, 是激光噪声抑制的下限. 本文通过选定低噪声基准芯片及数模转换芯片, 设计外控电路、采用低温漂系数元件、通过精密布板及电磁屏蔽等方案, 研发高精度低噪声程控电压基准源; 并通过可编程逻辑门阵列模块编程控制数模转换, 实现程控电压基准源输出电压精密变化. 结果表明: 所研发的电压基准源输出电压范围为–10 V—+10 V, 输出电压分辨率达20 bit, 在空间引力波频段输出电压的相对噪声谱密度低于9.6 ×10–6 Hz–1/2, 基准源噪声性能均优于相应引力波探测中对激光强度噪声要求, 为引力波探测中激光强度噪声抑制等方面提供关键器件支撑.

     

    Gravitational wave detection plays an important role in exploring the universe and opening up a new chapter for multi-messenger astronomy. As the most common device used for space and ground-based gravitational wave detection, large-scale laser interferometer requires a low-noise laser as a beam source. The noise of the laser can be suppressed by utilizing the optoelectronic negative-feedback noise reduction technology to improve the sensitivity of large-scale laser interferometer. The optoelectronic negative-feedback control system can suppress laser noise by subtracting the photodetector signal from the voltage reference signal, and then calculating the modulated signal by a proportional integral differentiator to control the output power of the pump current driver. Since the photodetector signal is affected by the laser intensity, its output voltage varies within a certain range, which requires that the output voltage of the voltage reference source signal is variable. In addition, the performance of the voltage reference directly affects the overall performance of the feedback control loop, therefore it is the lower limit of laser noise suppression. We develop a high-precision low-noise program-controlled voltage reference by selecting low-noise reference chip and digital-to-analog conversion chip, designing external control circuit, using low-temperature drift coefficient components and using temperature control and electromagnetic shielding. The digital-to-analog conversion is controlled through the FPGA module programming to accurately realize the reference voltage change. The output voltage range of the developed voltage reference source is from negative 10 V to positive 10 V and the minimal precision of the voltage variation is 20 bit. The voltage noise spectral density of the developed voltage reference is below 9.6 \times 10^ - 6/\sqrt \rm Hz and the noise performance of the reference source is less than the laser intensity noise in the space-based gravitational wave frequency band. The developed voltage reference source provides an important technical support for laser intensity noise suppression in gravitational wave detection.

     

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