Envelope-based technique for liquid level sensors using an in-line fiber Mach–Zehnder interferometer

Abstract

This paper proposes a sensor interrogation technique based on the analysis of the overall spectrum envelope of an in-line Mach-Zehnder interferometer structure with three different fibers. The interference pattern created by a level sensor of 120 mm was evaluated with both the traditional and the proposed interrogation techniques. The result shows that the technique here proposed improves the sensitivity of the sensor by more than an order of magnitude. Moreover, our new interrogation technique allows the length of an in-line Mach-Zehnder interferometer to be extended up to 470 mm while maintaining high linearity and sensitivity.

Analytical Analysis and Experimental Validation of a Multi-parameter Mach-Zehnder Fiber Optic Interferometric Sensor

“…Zehnder, [1], [3], [5]- [7]. It has been widely seen that for each sensor constructed, values such as their sensitivity and operational range is often highly dependent on the sensors length.…”

“…Interferometric sensors such as [1], [3]- [5] use interrogation techniques based on the spectrum obtained by the interference of light beams propagating inside the optical fiber through different routes. The idea is to give the light two paths; one being influenced by the external environment while the other is not.…”

“…Measurements of liquid level, [1]- [3], temperature, [1], refractive index, [1], [4], and angles can be very accurate when performed by optical interferometric sensors.…”

Nano silica diaphragm in-fiber cavity for gas pressure measurement

“…Various types of fiber optic sensors, such as long period fiber gratings 1–3 , fiber Bragg gratings 4–6 , Mach-Zehnder interferometers (MZIs) 7–9 , and Fabry-Perot interferometers (FPIs) 10–27 , have been reported to fulfill specific gas pressure application. Among the above gas pressure sensors, FPI-based sensors have played a dominant role due to their capacity for miniature size and ultra-high sensitivity.…”

Low-Cost Interrogation Technique for Dynamic Measurements with FBG-Based Devices

“…The popularization and fast growth of optical fiber sensing technology has stimulated much research in different areas, such as industrial, medical, aerospace, civil, and so on, where measurements of diverse physical and chemical parameters, such as acceleration, level, temperature, strain, pressure, deformation, refractive index, among others, are required. Optical fiber sensors (OFSs) have been developed and broadly used for these measurements [ 1 , 2 , 3 , 4 , 5 , 6 ]. This technology has important features such as intrinsic safety, resistance to chemical corrosion, immunity to electromagnetic interference, electric isolation, small size, lightweight sensing heads, high resolution, easy multiplexing, and capability for extremely remote monitoring without the need of electrical power at the measuring point [ 7 , 8 ].…”