Polymer optical fiber for large strain measurement based on multimode interference

Abstract

This Letter reports a polymer optical fiber (POF) based large strain sensor based on the multimode interference (MMI) theory for the application of structural health monitoring. A section of POFs is sandwiched between two silica single mode fibers to construct a single-mode-multimode-single-mode structure that produces a MMI spectrum. The strain sensing mechanism of the device was investigated and experimentally verified. A large dynamic range of 2×10(4) με (2%) and a detection limit of 33 µε have been demonstrated.

Strain-induced spectral tuning of the whispering gallery modes in a cylindrical micro-resonator formed by a polymer optical fiber

“…The second assumption is that there is a measurable change in the refractive index brought about by the different mechanical stress and strain components within the resonator material. Taken together, the fractional change in the wavelength of the WGMs is [21][22][23][24][25][30][31][32] Δλ λ ΔD D Δn n ;…”

“…where P eff is the effective strain-optic coefficient [25,32]. Subsequently, the WGM resonance wavelength shift can be expressed as…”

“…The Poisson ratio and the effective strain-optic coefficient of PMMA are 0.35-0.45 and 0.099 ( 0.0009), respectively, [20,25,32,33]. By assuming the Poisson's ratio (σ) of the POF is 0.35, the theoretical calculation based on Eq.…”

A Packaged Whispering Gallery Mode Strain Sensor Based on a Polymer-Wire Cylindrical Micro Resonator

“…There are many reports on fiber optic strain sensors employing single mode and multimode polymer optical fibers (POFs) as strain sensors including FBGs written in conventional and micro-structured POF [3,4]. A POF multimode interference sensor has also been reported [5]. It should be noted however, that the polymer sensor types above require substantial effort in terms of fabrication and cost (for example FBG writing, photomasks, fiber hetero-structure fabrication, depending on the sensor type).…”

Large strain detection of SRM composite shell based on fiber Bragg grating sensor

“…Huang et al [5] achieved 2% strain measurement through the multi-mode interference polymer fiber. Kim et al [6] used metal coated optical fiber sensors to determine the maximum strains experienced by composite structures.…”