High-sensitivity strain sensor based on in-fiber improved Fabry–Perot interferometer

Abstract

We demonstrated a high-sensitivity strain sensor based on an in-fiber Fabry-Perot interferometer (FPI) with an air cavity, which was created by splicing together two sections of standard single-mode fibers. The sensitivity of this strain sensor was enhanced to 6.0 pm/με by improving the cavity length of the FPI by means of repeating arc discharges for reshaping the air cavity. Moreover, such a strain sensor has a very low temperature sensitivity of 1.1 pm/°C, which reduces the cross sensitivity between tensile strain and temperature.

Magnetic field sensing with an in-line Fabry-Perot interferometer based on capillary optical fiber and Terfenol-D

“…These results are consistent with typical values reported in literature: around 5pm/µɛ for axial strain for cavities with length less than 60 µm [14][15] , and 1 pm/ o C for temperature 6 .…”

“…Also, since FBGs and the magnetostrictive material used are sensitive to temperature, some type of temperature compensation must be performed, so as to not incorrectly interpret temperature variations as temperature variations 6-7 . In-line fiber optic Fabry-Perot Interferometers (FPIs), on the other hand, are less sensitive to temperature variations and may be more sensitive to strain variations, depending on the type 8 . Intrinsic FPIs can be formed by building an air-cavity contained in the fibers with hollow-core or photonic crystal fibers 9-12 or by creating a spherical air-bubble inside the fibers during the fusion splice [13][14][15] .…”

High temperature strain sensor based on a fiber Bragg grating and rhombus metal structure

“…Until now, various techniques based on optical fiber sensing can achieve this purpose. These approaches mainly include techniques based on long period fiber gratings (LPFGs) [3,10], Fabry-Perot interferometers (FPIs) [11][12][13], and fiber Bragg gratings (FBGs) [4]. However, for the LPFG sensors, not only is the 3 dB bandwidth larger than that of the FBGs, making them limited to precise measurements and multiplexing, but there is also some complexity in demodulating the transmission signal.…”

Open-Cavity Fabry-Perot Interferometer Based on Etched Side-Hole Fiber for Microfluidic Sensing

“…Compared to the open-cavity ones, the sealed-cavity FPIs have been widely developed for different types of applications. In the previous works, a sealed-cavity type FPI with an in line air bubble, attained by fusion technologies, successfully demonstrated the capabilities of high strain sensitivity and very low temperature-cross sensitivity [3], [4]. Similarly, air-sealed FPIs have also been obtained by employing special fibers or tubes such as silica capillaries and photonic crystal fibers [5]- [7].…”