Ultrasensitive Temperature Sensor With Cascaded Fiber Optic Fabry–Perot Interferometers Based on Vernier Effect

Abstract

We have proposed and experimentally demonstrated an ultrasensitive fiber-optic temperature sensor based on two cascaded Fabry-Perot interferometers (FPIs). Vernier effect that significantly improves the sensitivity is generated due to the slight cavity length difference of the sensing and reference FPI. The sensing FPI is composed of a cleaved fiber end-face and UV-cured adhesive while the reference FPI is fabricated by splicing SMF with hollow core fiber. Temperature sensitivity of the sensing FPI is much higher than the reference FPI, which means that the reference FPI need not to be thermally isolated. By curve fitting method, three different temperature sensitivities of 33.07, −58.60, and 67.35 nm/°C have been experimentally demonstrated with different cavity lengths ratio of the sensing and reference FPI, which can be flexibly adjusted to meet different application demands. The proposed probe-type ultrahigh sensitivity temperature sensor is compact and cost effective, which can be applied to special fields, such as biochemical engineering, medical treatment, and nuclear test.

Optical Vernier Effect: Recent Advances and Developments

“…The series configuration with physically separated FPIs seemed very promising however, it only started to enter mainstream use since 2018. [12,14,[16][17][18][19] Prior to then, only a few publications with the interferometers physically connected to each other were published. [20][21][22] Overall, the optical Vernier effect configurations using only FPIs, the case of two FPIs physically connected in series was the most studied, corresponding to almost half of the publications within this group.…”

“…In terms of applications, the configurations using FPIs were mainly used for temperature [15,16,20,23,25,29,30,32,34,38] and strain sensing. [9,12,18,19,35] Apart from these two applications, others such as magnetic field sensing, [9] gas refractive index, [21,26] and pressure sensing, [17,24] airflow sensing, [22] hydrogen sensing, [14] humidity sensing, [13] volatile organic compounds sensing, [28] and refractive index sensing of liquids [31] were also reported.…”

Fabrication and Qualitative Analysis of an Optical Fibre EFPI-Based Temperature Sensor

“…Several methods have been reported in the literature for creating high-sensitivity diaphragms on EFPIs. These have typically been an involved process requiring several sub-assemblies relying on adhesives, micro-machining, or multiple fusion steps [ 17 , 18 , 19 , 20 ]. One such EFPI is that proposed by Li et al [ 17 ], where the diaphragm thickness is in the region of 8 μm.…”

Sensitivity Enhancement of Ultrahigh-Order Mode Based Magnetic Field Sensor via Vernier Effect and Coarse Wavelength Sampling

“…By means of this, the sensor structure can be greatly simplified and the sensitivity can be controlled and improved. It is believed that this method can be applied to other Vernier-effect based sensors, such as strain sensor [13], temperature sensor [14,15], etc. The schematic diagram of the magnetic field sensor is depicted in Fig.…”