Fiber-optic bending vector sensor based on Mach–Zehnder interferometer exploiting lateral-offset and up-taper

Abstract

A simple, compact, and highly sensitive optical fiber directional bend sensor is presented. This device consists of a lateral-offset splicing joint and an up-taper formed through excessive fusion splicing method. The lateral-offset splicing breaks the cylindrical symmetry of the fiber and defines a pair of directions along which the bending response of the Mach-Zehnder interferometer transmission spectrum is different and thus could be used for bending vector measurement. For a curvature range from -3 to 3 m(-1), the bending sensitivities at 1463.86 nm and 1548.41 nm reach 11.987 nm/m(-1) and 8.697 nm/m(-1), respectively.

Simultaneous measurement of one dimensional bending and temperature based on Mach-Zehnder interferometer

“…The wavelength shift is insensitive to applied bending in the curvature range from 0 to 7.13 m 1 , and the bending sensitivity is found no directional characteristic. It is due to that the structure of the MZI is symmetric in the X axis direction, and thus the optical path difference (OPD) of the MZI with the applied curvature will almost be unchanged for the fiber orientations at 90° and 270°, meanwhile resulting in the same attenuation wavelength shifts in the opposite direction [7]. It indicates that this structure of the MZI can work as a one-dimensional bending vector sensor.…”

“…We consider that it is because the interference pattern of the MZI is resulted by In practical applications, it is beneficial to avoiding cross-sensitivity of temperature in bending measurements. Here in our experiments, both Dip-A and Dip-B show linear and discriminating sensitivities to curvature and temperature, so the structure of the MZI can be used to measure curvature and temperature simultaneously by constructing a matrix consisting of the bending and temperature sensitivities [7,16]. The sensing matrix can be determined in (7): …”

Recent Developments in Micro-Structured Fiber Optic Sensors

“…The tapered fiber section enhanced the sensitivity of the RI measurement. Other similar structures include the up taper cascaded with offset splicing [283] and FBG [284] for bending vector and displacement measurements.…”

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.…”