A compact, highly sensitive optical fiber temperature sensor based on a cholesteric liquid crystal polymer film.

Liquid crystals (LCs) are commonly used to enhance the temperature sensitivity of fiber optic temperature sensors. Most studies utilized non-polymerizable LC-filled optical fibers, which suffer from drawbacks such as complex structure, low temperature detection capability, and narrow measurement range. In this study, a temperature sensor with a wide measurement range, high sensitivity, and simple fabrication process was proposed by directly integrating polymerizable cholesteric liquid crystal (CLC) films onto the end face of optical fibers. The effects of various components in CLC on temperature response were investigated and the temperature sensor fabricated from sample Ⅱ-4 exhibited the best performance. It can detect temperatures ranging from 30 to 270 °C. Within the range of 30–150 °C, its sensitivity is 381 pm/°C, while from 150 to 270 °C, the sensitivity increases to 879 pm/°C. Moreover, it achieves a rapid response time of just 300 ms. Its small size allows monitoring in confined spaces, expanding LC sensor applications. • A temperature sensor integrating polymer liquid crystal films with optical fibers was proposed, enhancing the stability of temperature measurement in optical fiber sensors filled with liquid crystal. • Incorporating the thermally responsive material improved the maximum detectable temperature of liquid crystal-filled temperature sensors and expanded the temperature measurement range. • The sensor features simple fabrication, compact structure, high sensitivity, and with a wide temperature measurement range, making it suitable for temperature detecting micron-scale spaces. [ABSTRACT FROM AUTHOR]