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A temperature measurement subsystem (TMS) is a critical piece of infrastructure of the space gravitational wave detection platform, necessary for monitoring minuscule temperature changes at the level of 1 μ K / Hz 1 / 2 within the electrode house, in the frequency range of 0.1 mHz to 1 Hz . The voltage reference (VR), a key component of the TMS, must possess low noise characteristics in the detection band to minimize the impact on temperature measurements. However, the noise characteristics of the voltage reference in the sub-millihertz range have not been documented yet and require further study. This paper reports a dual-channel measurement method for measuring the low-frequency noise of VR chips down to 0.1 mHz . The measurement method makes use of a dual-channel chopper amplifier and an assembly thermal insulation box to achieve a normalized resolution of 3 × 10 − 7 / Hz 1 / 2 @ 0.1 mHz in the VR noise measurement. The seven best-performance VR chips documented at a common frequency range are tested. The results show that their noise at sub-millihertz frequencies can significantly differ from that around 1 Hz . [ABSTRACT FROM AUTHOR]

• A novel fiber optic temperature sensor based on multimode interference is proposed. • The sensitivity is improved by splicing NCFs with different diameters and tapered fusion. • An ultra-high temperature sensitivity of −14.448 nm/K is achieved. • The reproductivity and repeatability of the proposed sensor are remarkable. For the advancement of temperature monitoring devices, research into high sensitivity fiber optic temperature sensors is valuable. This research suggests a fiber optic temperature sensor with great sensitivity. Specifically, the NCF (no core fiber) spliced with various diameters is employed within the multimode interference region of the typical SNS (single mode fiber-no core fiber-single mode fiber) sensor. The morphology of the splice sites connecting two NCFs is also regulated by fusing. The mixture of ethanol and glycerol is used to coat the entire structure. According to the experimental results, the proposed sensor can achieve a temperature sensitivity of −14.448 nm/°C. Additionally, the sensor has good performance in repeatability and temperature cycling thanks to its simple, dependable structure. It is anticipated that the relevant results will be useful for the development and applications of precise temperature measurement. [ABSTRACT FROM AUTHOR]

Single-mode-no-core-single-mode (SNS) optical fiber structures have valuable potential to encapsulate as high-precision temperature sensors, due to their great sensitivity. This paper is to improve the temperature sensitivity of SNS fibers by studying the parameters of fiber length, diameter, and refractive index of the seal liquid. Transmission spectra of the fibers are given in both aspects of experiment and numerical simulation. We find that using a slim no-core fiber section sealed with liquid of high refractive index can effectively improve the sensitivity, while the choice of fiber length mainly affects the width of transmission peak. The results may contribute to the development of high-sensitivity optic temperature sensor. [ABSTRACT FROM AUTHOR]