Use of 3×3 Coupler in the Fiber Optic Strainmeter Based on Mach-Zehnder Interferometer

Abstract

In this paper a strainmeter based on the fiber optic Mach-Zehnder interferometer with 3x3 coupler for a phase shift demodulation is presented. Laboratory experiments on registration of harmonic deformation with the use of strainmeter were carried out.The experiment demonstrates efficiency of the strainmeter.

Vital Signs Monitoring Based on Interferometric Fiber Optic Sensors

“…In the experiment, even if the optical path difference between the two arms is adjusted to π/2 in advance, the optical path difference between the two arms cannot be maintained at π/2 in the static state due to the slowly random phase drift noise and temperature changes. In order to solve this problem and make the FOS based on interferometer work stably, many demodulation schemes have been proposed [24][25][26][27][28][29][30][31][32][33][34]. However, there are some problems when demodulating vital signs signals based on optical fiber interferometers.…”

“…O.T. Kamenev et al used this scheme for the fiber optic MZI-based strainmeter [31], and D. Xu et al used the same scheme to measure the phase and frequency noise of the Michelson interferometer [32]. S. Park et al have achieved nanometer-scale displacement or vibration measurement using an interferometer based on a 3 × 3 fiber circulator [33,34].…”

“…Due to the high cost of the FBG sensors and the limited sensitivity of the intensity-based sensors, researchers chose the interferometric FOS for vital signs monitoring. Researchers have dedicated much time and effort to the design of sensor structures [12][13][14][15][16][17][18][19][20][21][22][23], demodulation methods [12,[24][25][26][27][28][29][30][31][32][33][34][35][36] and the application of vital signs monitoring [12][13][14]16,[18][19][20][21][22][23][35][36][37][38][39][40][41][42][43][44][45].…”