Strain-, curvature- and twist-independent temperature sensor based on a small air core hollow core fiber structure

Abstract

Cross-sensitivity (crosstalk) to multiple parameters is a serious but common issue for most sensors and can significantly decrease the usefulness and detection accuracy of sensors. In this work, a high sensitivity temperature sensor based on a small air core (10 µm) hollow core fiber (SACHCF) structure is proposed. Co-excitation of both anti-resonant reflecting optical waveguide (ARROW) and Mach-Zehnder interferometer (MZI) guiding mechanisms in transmission are demonstrated. It is found that the strain sensitivity of the proposed SACHCF structure is decreased over one order of magnitude when a double phase condition (destructive condition of MZI and resonant condition of ARROW) is satisfied. In addition, due to its compact size and a symmetrical configuration, the SACHCF structure shows ultra-low sensitivity to curvature and twist. Experimentally, a high temperature sensitivity of 31.6 pm/°C, an ultra-low strain sensitivity of −0.01pm/µε, a curvature sensitivity of 18.25 pm/m−1, and a twist sensitivity of −22.55 pm/(rad/m) were demonstrated. The corresponding temperature cross sensitivities to strain, curvature and twist are calculated to be −0.00032 °C/µε, 0.58 °C/m−1 and 0.71 °C/(rad/m), respectively. The above cross sensitivities are one to two orders of magnitude lower than that of previously reported optical fiber temperature sensors. The proposed sensor shows a great potential to be used as a temperature sensor in practical applications where influence of multiple environmental parameters cannot be eliminated.

All-Fiber In-Line Twist Sensor Based on a Capillary Optical Fiber

“…We think that the former is due to multi-beam interference in the capillary, and that when the phase differences between all propagating modes fit a particular condition, only one resonance is formed. For the latter, most of the power from the lead-in SMF is coupled into the excited circular symmetrical modes [29], and just a small amount of power is coupled into some low-order noncircular symmetrical modes that are stimulated randomly and are passively reliant on the capillary fiber topology. During the twist operation, the power exchange between the circular and noncircular modes is relatively minimal, and this power exchange is independent of the twist direction.…”

Construction of multiple anti-resonant light guidance mechanisms in a hollow-core fiber structure for simultaneous measurement of multiple parameters

“…Based on above definition, for dip II the bare HCF structure has an RI sensitivity of 400 nm/RIU, and a slightly reduced sensitivity of 340±15 nm/RIU for that partially PI coated HCF structure. This is reasonable since the final spectral response is a superposition of the spectra excited by a bare HCF structure and a PI-coated HCF structure and the dips sensitivities are influenced by the degree of their spectral overlap (a phase difference between two different resonant conditions) [1]. This could also explain why some of the dips of type I have a slightly larger wavelength shift.…”

“…© 2022 Optica Publishing Group Cross sensitivity from multiple parameters has been a serious issue for optical fiber sensors (OFSs) since it can render some sensors unusable in some cases (for example, due to failure of a material at high temperatures) or can significantly decrease the detection accuracy of a sensor. One possible solution to overcome this problem is to fabricate a high sensitivity OFS to the target parameter but with an inherent low cross-sensitivity to other possible encountered parameters [1][2][3]. For example, in our previous work a temperature sensor was proposed based on a small air core hollow core fiber (HCF) structure with ultra-low cross sensitivities to strain, curvature and twist [1].…”

“…One possible solution to overcome this problem is to fabricate a high sensitivity OFS to the target parameter but with an inherent low cross-sensitivity to other possible encountered parameters [1][2][3]. For example, in our previous work a temperature sensor was proposed based on a small air core hollow core fiber (HCF) structure with ultra-low cross sensitivities to strain, curvature and twist [1]. Zhong et al developed a high sensitivity temperature-independent humidity sensor based on a U-shaped plastic optical fiber evanescent-wave sensor coated with polyimide (PI) and graphene oxide layers [2].…”

Double Antiresonance Fiber Sensor for the Simultaneous Measurement of Curvature and Temperature

“…The acquired sensitivities for the temperature and curvature were 25.76 pm/°C and −4.28 dB/m −1 , respectively. Further sensors have already been developed to measure these parameters [ 38 , 39 ].…”