Highly sensitive temperature sensor based on a liquid crystal selectively infiltrated two-core photonic crystal fiber

Abstract

This article proposes a temperature sensor based on liquid crystal selectively filled two-core photonic crystal fiber featuring high sensitivity and compact structure. In order to achieve the purpose of compact structure and temperature sensing, we consider to combine the temperature-sensitive material liquid crystal (LC) E7 and photonic crystal fiber to study the performance of temperature sensing. Since the applied electric field and temperature have great influence on the arrangement of liquid crystal molecules, LC as a temperature sensitive material can improve the sensing performance. An air hole filled with LC isolates the two horizontal cores, where the two horizontal cores act as two separate waveguides and the LC core is used to regulate the mode coupling of the two horizontal cores. In the process of transferring light energy from one core to another, the position of the transmission spectrum of the sensor is changed by optimizing the diameter of LC core and horizontal two-core, and then a sensor with high sensitivity and stable performance is designed. The coupling length and transmission spectrum of the sensor are analyzed by using full vector finite element method. By analyzing the wavelength dips of the transmission spectrum, the maximum sensitivity of the proposed temperature sensor can be reached −6.69 nm/℃ at 30 ℃ for Y-polarized (Y-Pol) direction. The main advantages of the sensor proposed in this paper are simple structure and easy to manufacture, high sensitivity and high fitting coefficient.