A Novel Strain Sensor with Large Measurement Range Based on All Fiber Mach-Zehnder Interferometer

Abstract

We have proposed a high sensitive photonic crystal fiber (PCF) strain sensor based on the Mach-Zehnder interferometer (MZI). The sensing head is formed by all-fiber in-line single mode-multimode-photonic-crystal-single mode fiber (SMPS) structure, using only the splicing method. Such a strain sensor exhibited a high sensitivity of −2.21 pm/με within a large measurement range of up to 5000 με and a large fringe visibility of up to 24 dB. Moreover, it was found that the strain sensitivity was weekly dependent of the length of PCF or MMF. In addition, the sensor exhibited the advantages of simplicity of fabrication, high sensitivity and larger fringe visibility.

Advances on Photonic Crystal Fiber Sensors and Applications

“…A wide class of interferometric photonic crystal fiber (PCF) sensors are based on the idea of using the core and the cladding of a single-core PCF as the sensing and the reference arm of an interferometer, respectively [15,16,17]. As evidenced in the introduction, this operation principle is also exploited in other sensors which could be classified by considering a different criterion as the employed material of the kind of light matter interaction, see the last case of previous section.…”

“…In [15] an all-fiber in-line Mach-Zehnder interferometer (MZI) strain sensor is experimentally demonstrated. As shown in Figure 7, the MZI sensor is fabricated with a 50/125 μm multimode fiber (MMF) and a 10.1/125 μm photonic crystal fiber (PCF) spliced between two identical single mode fibers (SMFs) working in the C+L optical band (1528 ÷ 1602 nm).…”

“…A strain sensitivity of −1.21 pm/με is obtained for a 40 mm-length PCF. The experimental measurements reported in Figure 8 show that the length of the MMF or PCF do not have a strong influence on the strain sensitivity [15]. Moreover, an interference fringe visibility of 24 dB is obtained [15].…”

“…( a ) All-fiber Mach-Zehnder interferometer strain sensor based on an in-line SMF-MMF-PCF-SMF structure; ( b ) Cross-section of the PCF. Adapted from [15]. …”

“…It is not exhaustive due to the very large literature production. The focus is on: (i) plasmonic [3,4,5,6,7,8,9,10,11,12,13,14], (ii) interferometric [15,16,17,18,19] and (iii) grating-based [20,21,22,23,24,25,26,27,28,29,30,31,32] PCF sensors, discussed in the following Section 2, Section 3 and Section 4, respectively. In other cases, innovative materials as graphene, polyvinyl alcohol, ferrofluid liquids, combined with the exploitation of conventional principles as the interferometry or the evanescent field interaction are simultaneously applied to obtain novel and promising devices.…”