Fiber curvature sensor based on concave‐heterotypic cascaded fiber Sagnac interferometer

Abstract

A fiber optical curvature sensor comprising a concave‐heterotypic cascaded fiber structure built into Sagnac loop is demonstrated experimentally. A section of multimode fiber is sandwiched between the single mode fiber and polarization maintaining fiber in order to construct the concave‐heterotypic cascaded fiber structure. The concave structure presented is used to effectively excite guided modes. The spectra of the proposed bending sensor will shift toward long wavelength with curvature. The measured the curvature sensitivity of 11.6 nm/m−1 has been achieved. The proposed curvature sensor characterizes cost‐efficient, simple fabrication process and can be used for health monitoring in civil engineering.

Fiber-Optic Microstructure Sensors: A Review

“…Among manifold fiber-optic sensors, the fiber-optic microstructure (FOM) sensor, formed by introducing microstructure into optical fiber, is one of the most important devices since it offers unique characteristics of high sensitivity, high resolution, and excellent distributing and multiplexing capabilities. To date, the FOM sensors mainly include fiber Bragg grating (FBG) sensors [1,2], long-period fiber grating (LPFG) sensors [3,4], Fabry-Perot interferometer (FPI) sensors [5,6], Mach-Zehnder interferometer (MZI) sensors [7,8], Michelson interferometer (MI) sensors [9,10], and Sagnac interferometer (SI) sensors [11,12]. Each FOM sensor possesses abundant structures and its fabrication technologies are also various, including chemical etching [13], excimer laser micromachining [14], femtosecond laser micromachining [15], CO 2 laser micromachining [16], focused ion beams (FIB) milling [17], and kinds of coating technologies, just to name a few.…”

High sensitivity Sagnac interferometric strain sensor based polarization maintaining fibre enhanced coupling

“…Optical fibre SI constructed by a 3‐dB coupler and a high birefringence fibre has been investigated many years since its first proposal and has been developed into various sensors, such as strain [16,17], temperature [18,19] and curvature [20] sensors taking advantage of the merits of simple configuration, flexible operation and high sensitivity.…”

A Simple Optical Sensor Based on Multimodal Interference Superimposed on Additive Manufacturing for Diameter Measurement

“…Multimodal Interference (MMI) devices based on optical fibers have been extensively investigated and act as sensors in recent years for different applications, such as temperature [10], strain [11][12][13], air pressure [14], vibration [15], gasohol quality [16], structure health monitoring [17], flow rate [18,19], and so on. There exist several types of MMI structures, such as the Sagnac Interferometer [20], Fabry-Perot Interferometer [21], and Singlemode-Multimode-Singlemode (SMS) [22]. One of the most common MMI structures is the SMS [22,23].…”