Optical Fiber Temperature and Torsion Sensor Based on Lyot-Sagnac Interferometer

Abstract

An optical fiber temperature and torsion sensor has been proposed by employing the Lyot-Sagnac interferometer, which was composed by inserting two sections of high-birefringence (HiBi) fiber into the Sagnac loop. The two inserted sections of HiBi fiber have different functions; while one section acts as the temperature sensitive region, the other can be used as reference fiber. The temperature and twist sensor based on the proposed interferometer structure have been experimentally demonstrated. The experimental results show that the envelope of the output spectrum will shift with the temperature evolution. The temperature sensitivity is calculated to be −17.99 nm/°C, which is enlarged over 12 times compared to that of the single Sagnac interferometer. Additionally, the fringe visibility of the spectrum will change due to the fiber twist, and the test results reveal that the fringe visibility and twist angle perfectly conform to a Sine relationship over a 360° twist angle. Consequently, simultaneous torsion and temperature measurement could be realized by detecting the envelope shift and fringe visibility of the spectrum.

The impact of polarization‐maintaining and multimode fibre lengths on strain and temperature sensitivities of single‐mode–multimode–polarization‐maintaining–multimode–single‐mode‐based fibre optic sensors

“…Compared with Refs. [11][12][13][14][15]19,[22][23][24], the proposed SMPMS temperature sensor shows a high sensitivity of 2.366 nm/°C. At the same time, compared with the sensing structure of the reference, this structure has the advantages of higher sensitivity, simple manufacture and low cost.…”

A review of optical interferometry techniques for VOC detection

“…The Sagnac interferometer is used in filtering, communications and sensor applications due to its simple design, ease of fabrication and lower susceptibility to external noise [59]. It has been applied for gas detection [47], pressure [59], temperature [60], humidity [61], and strain measurements [62]. The Sagnac interferometer is usually applied in a ring configuration, or fiber loop mirror for gas sensing, as shown in Figure 3(B).…”

Fiber Ring Laser Directional Torsion Sensor with Ultra-Wide Linear Response

“…To date, fiber torsion sensors have played indispensable roles in aerospace engineering, artificial intelligence, and industrial automation due to the merits of their compact size, high sensitivity, low cost, and immunity to electromagnetic interference. Lots of schemes have been demonstrated based on fiber gratings [1,2,3,4,5,6], modal interferometers [7,8,9,10], Sagnac interferometers (SI) [11,12,13,14,15,16,17,18], microfibers [19,20], and multi-/hollow-core fibers [21,22,23]. Among them, polarization-maintaining fiber (PMF) based Sagnac-loop structures are viewed as one of the most practical torsion sensors owing to their stability and cost-efficiency.…”