LAUSR

Abstract A sensitivity enhanced temperature sensor with cascaded Sagnac loops based on harmonic Vernier effect has been proposed and verified by experiments. The harmonic Vernier effect can be achieved, through controlling the polarization-maintaining fiber (PMF) length of one Sagnac loop to be an integral multiple of the other with a small deviation. The experimental results show that in temperature range of 30–70 °C, the temperature measurement sensitivity of the proposed sensor device based on the harmonic Vernier effect is 3.66 nm/°C, which is 22.5 times that of the single Sagnac loop (0.163 nm/°C), and 1.7 times that of the sensor based on the basic Vernier effect (2.12 nm/°C). Thanks to the advantages of the proposed sensing structure’s high sensitivity and full fiber configuration, it can be used in various specific fields, such as power grids and mines.