Simultaneous measurement of strain and temperature by employing fiber Mach-Zehnder interferometer

Abstract

We demonstrated a novel fiber in-line Mach-Zehnder interferometer (MZI) with a large fringe visibility of up to 17 dB, which was fabricated by misaligned splicing a short section of thin core fiber between two sections of standard single-mode fiber. Such a MZI could be used to realize simultaneous measurement of tensile strain and temperature. Tensile strain was measured with an ultrahigh sensitivity of -0.023 dB/μɛ via the intensity modulation of interference fringes, and temperature was measured with a high sensitivity of 51 pm/°C via the wavelength modulation of interference fringe. That is, the MZI-based sensor overcomes the cross-sensitivity problem between tensile strain and temperature by means of different demodulation methods. Moreover, this proposed sensor exhibits the advantages of low-cost, extremely simple structure, compact size (only about 10 mm), and good repeatability.

Temperature effects of Mach-Zehnder interferometer using a liquid crystal-filled fiber

“…Using our LC-infiltrated MZI, we have achieved a temperature sensitivity/tuning capability of ~−1.55 nm/°C in the temperature range between 25°C and 77°C. This sensitivity is about 30X higher than that of previously developed MZIs with a misalignment-spliced joint (51 pm/°C) [12] and micro air-cavity (44.1 pm/°C) [15]. Thus, our LC-based MZI has potential applications as a high wavelength-tunable photonic device or a high sensitivity temperature sensor.…”

“…There are many ways to realize an in-fiber MZI. A common method is to induce and recombine the core mode and cladding modes of a SMF by using double fiber corners [6], long-period fiber grating (LPFG) [7,8], optical fiber taper [9][10][11], misalign spliced joint [12], microstructure collapsing on a photonic crystal fiber [13], imbedded micro air-cavity in fiber [14,15], etc. However, these techniques require complicated process or expensive fabrication apparatus, which knowingly limit their practical applications.…”

High temperature probe sensor with high sensitivity based on Michelson interferometer

“…Compared with conventional electric sensors, a growing interest on temperature sensors based on optical fibers has been arisen due to their well known advantages of immunity to electromagnetic interference, compactness, high accuracy, ease fabrication, and capability of sensing in harsh environment. At present, a variety of optical fiber sensors [1,2], such as Fiber Bragg grating (FBG) [3,4], long-period fiber grating (LPG) [5,6], Mach-Zehnder interferometer(MZI) [7][8][9][10][11][12][13], Fabry-Perot interferometer (F-P) [14][15][16][17] have been studied extensively. In particular, with the method of Michelson interferometer [18][19][20] to measure temperature becomes a new trend.…”

Multicore microstructured optical fibre for sensing applications

“…A specific type of the MZI is an in-line MZI whereby all interferometer arms are integrated into one optical fibre. For example in-line configurations can exploit twin core fibres [5,6], air hole collapsing of microstructured optical fibre (MOF) [7,8], core mismatch [9,10], a multimode fibre segment [11] or fibre tapering [4]. These configurations exhibit good performance when sensing strain, temperature and bending.…”