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

Abstract

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 <inline-formula><tex-math id="M1">\begin{document}$9.6 \times 1{0^{ - 6}}/\sqrt {\rm Hz}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20222119_M1.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20222119_M1.png"/></alternatives></inline-formula> 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.