Strain sensor using twisted optical fibers

Abstract

A novel sensor using twisted optical fibers is proposed to detect distributed tensile strain. This sensor converts tensile strain to optical loss. The relation between tensile strain and optical loss is modeled and experimentally confirmed for uniform tensile strain.

Co-Axial, Double Waveguide Single-Mode Fiber Coupler

“…1C ^1 E* A, J c core ' E clad e '^Z dv (1) We see that the light is mostly coupled to modes which have the same propagation constant and similar behavior as the LP Q ,-mode when the fiber is bent. That is the reason for nearfield behaviour seen in the figure 2, where the fiber was bent on a single turn having radius of 19 mm.…”

<title>Optical fiber sensors integrated with composite material based constructions</title>

“…Singlemode fiber r Measuring heads , which were also used for monitoring of deformation of the test composite layer and composite vessels, are optical fiber micro-bending sensors (MBS) [3]. They belong to a group of sensors with the lightwave length's modulation propagated in the measurement system.…”

“…Changes in attenuation of the micro-bending sensor head used for strain measurements occur as a result of the application of expansion forces. The relation of loss of the sensor head in the function of the fiber curvature radius is described as follows [3]:…”

“…Structure of micro-bending sensor (a)[3] and change in optical power in the strain function for the micro-bending head (b)…”

Twisted Dual-Cycle Fiber Optic Bending Loss Characteristics for Strain Measurement

“…It is well known that radiation loss occurs when an optical fiber is bent [ 12 , 13 , 14 , 15 , 16 ]. Many polymer optical fibers (POFs) have utilized the attenuation of optical power caused by bending-induced mode conversion [ 16 , 17 , 18 , 19 , 20 , 21 ]. Lu et al presented a POF displacement sensor that enhanced sensitivity using a bent and elongated grooved POF [ 16 ].…”