Modal interferometer based on hollow-core photonic crystal fiber for strain and temperature measurement

Abstract

In this work, sensitivity to strain and temperature of a sensor relying on modal interferometry in hollow-core photonic crystal fibers is studied. The sensing structure is simply a piece of hollow-core fiber connected in both ends to standard single mode fiber. An interference pattern that is associated to the interference of light that propagates in the hollow core fundamental mode with light that propagates in other modes is observed. The phase of this interference pattern changes with the measurand interaction, which is the basis for considering this structure for sensing. The phase recovery is performed using a white light interferometric technique. Resolutions of +/- 1.4 microepsilon and +/- 0.2 degrees C were achieved for strain and temperature, respectively. It was also found that the fiber structure is not sensitive to curvature.

Hollow Core Fiber Based Interferometer for High-Temperature (1000 °C) Measurement

“…It is clear from the figure that the HCF length has a limited influence on the temperature sensitivity. However, a greater length somehow shows a lower strain sensitivity of 0.46 pm/με, which is lower than many other fiber structures such as FBG (1.2 pm/με) [31], long-period fiber-grating (7.6 pm/με) [32] and hollow-core photonic crystal fiber (0.96 pm/µε) [33]. Usually, a strain change will introduce the variation of fiber length and hence the optical length change, resulting spectral wavelength shifts.…”

Investigation of a novel temperature-sensing mechanism based on strain-induced optical path-length difference in a multicore optical fiber

“…The resolutions were reported to be 1.4 µε and 0.2 • C for strain and temperature, respectively [8]. Four-core optical fibers were used previously in twoaxis bend measurement [3] and three-dimensional optical profilometry [9].…”

In-fiber modal interferometer based on dual-concentric-core photonic crystal fiber and its strain, temperature and refractive index characteristics

“…Based on the singlemode fiber (SMF) and multi-mode fiber (MMF), some work on the infiber modal interferometers has been reported [1][2][3]. The PCF based interferometers are also proposed with the different PCFs for various applications [4][5][6][7][8][9]. Choi et al proposed an all-fiber Mach-Zehnder type interferometers formed in PCF [4].…”

“…Choi et al proposed an all-fiber Mach-Zehnder type interferometers formed in PCF [4]. Aref et al presented a modal interferometer with hollow-core PCF for strain and temperature sensing [5]. Dong et al proposed a strain sensor using the polarization maintaining PCF based Sagnac interferometer [6].…”