Spectral Bandwidth Analysis Of High Sensitivity Refractive Index Sensor Based On Multimode Interference Fiber Device

Fiber optic structures based on multimode interference were investigated to the refractive index (RI) sensing. The proposed device is a singlemode-multimode-singlemode (SMS) structure, where the multimode section is a coreless fiber (MMF). The numerical analyses were carried out by beam propagation and modal expansion methods. Ultra-high sensitivity was obtained: 827 nm/RIU over a RI range of 1.30-1.44 and a maximum sensitivity of 3500 nm/RIU for RI∼1.43, considering △RI = 0.01. The dependence of spectral bandwidth was investigated taking into account the multimode fiber diameter and the coupling efficiency between modes at the input junction singlemode- multimode. © 2012 SPIE.8421Aguilar-Soto, J.G., Antonio-Lopez, J.E., Sanchez-Mondragon, J.J., May-Arrioja, D.A., Fiber optic temperature sensor based on multimode interference effects (2011) Proceedings of XVII Reunión Iberoamericana de Óptica & X Encuentro de Óptica, Láseres y Aplicaciones, Journal of Physics: Conference Series, 274, pp. 1-4Nguyen, L.V., Hwang, D., Moon, S., Moon, D.S., Chung, Y., High temperature fiber sensor with high sensitivity based on core diameter mismatch (2008) Optics Express, 16 (15), pp. 11369-11375Hatta, A.M., Rajan, G., Semenova, Y., Farrell, G., SMS fibre structure for temperature measurement using a simple intensity-based interrogation system (2009) Electronics Lett., 45 (21)Silva, S., Pachon, E.G.P., Franco, M.A.R., Hayashi, J.G., Malcata, F.X., Frazão, O., Jorge, P., Cordeiro, C.M.B., Ultra-high sensitivity-temperature fiber sensor based on multimode interference Applied Optics, , accepted to publicationWang, P., Brambilla, G., Ding, M., Semenova, Y., Wu, Q., Farrell, G., Investigation of single-mode-multimode-single-mode and single-mode-tapered-multimode-single-mode fiber structures and their application for refractive index sensing (2011) J. Opt. Soc. Am. B, 28 (5), pp. 1180-1186Wu, Q., Semenova, Y., Wang, P., Farrell, G., High sensitivity SMS fiber structure based refractometer-analysis and experiment (2011) Optics Express, 19 (9), pp. 7937-7944Jin, Y.X., Chan, C.C., Zhao, Y., Dong, X.Y., Refractive index measurement by using multimode interference (2011) Proceedings of 21st International Conference on Optical Fiber Sensors, Proc. of SPIE, 7753, pp. 77535FZhang, C., Li, E., Peng, L.V., Wang, W., A wavelength encoded optical fiber sensor based on multimode interference in a coreless silica fiber (2009) Proceedings of International Conference on Optical Instruments and Technology: Advanced Sensor Technologies and Applications, Proc. SPIE SPIE, 7157, pp. 71570HWang, P., Brambilla, G., Ding, M., Semenova, Y., Wu, Q., Farrell, G., High-sensitivity, evanescent field refractometric sensor based on a tapered, multimode fiber interference (2011) Opt. Lett., 36, pp. 2233-2235Mehta, A., Mohammed, W., Johnson, E.G., Multimode interference-based fiber-optic displacement sensor (2003) IEEE Photon. Technol. Lett., 15, pp. 1129-1131Hatta, A.M., Semenova, Y., Wu, Q., Farrell, G., Strain sensor based on a pair of single-mode-multimodesingle-mode fiber structures in a ratiometric power measurement scheme (2010) Appl. Opt., 49, pp. 536-541Silva, S., Frazão, O., Viegas, J., Ferreira, L.A., Araújo, F.M., Malcata, F.X., Santos, J.L., Temperature and strain-independent curvature sensor based on a singlemode/multimode fiber optic structure (2011) Meas. Sci. Technol., 22, p. 085201Soldano, L.B., Pennings, E.C.M., Optical multi-mode interference devices based on self-imaging: Principles and applications (1995) J. Lightwave Technol., 13 (4), pp. 615-62

Multimode Interference In Tapered Single Mode-multimode-single Mode Fiber Structures For Strain Sensing Applications

Tapering single mode-multimode-single mode structures to enhance sensitivity is proposed and experimentally demonstrated. 50 mm-long coreless MMF sections are spliced between SMFs and tapered. They are characterized in strain and an increase in strain sensitivity is obtained with taper diameter reduction. Sensitivities as high as -23.69 pm/με for the 15 μm taper are attained. A combination of an untapered and tapered SMS is proposed as a sensing system for the simultaneous measurement of strain and temperature. © 2012 SPIE.8421Soldano, L., Pennings, E., Optical multi-mode interference devices based on self-imaging: Principles and applications (1995) Lightwave Technology, Journal of, 13, pp. 615-627. , AprilKumar, A., Varshney, R.K., Sharma, P., Transmission characteristics of sms fiber optic sensor structures (2003) Optics Communications, 219, pp. 215-219Wang, Q., Farrell, G., Yan, W., Investigation on single-mode-multimode-single-mode fiber structure (2008) J. Lightwave Technol., 26, pp. 512-519. , MarMehta, A., Mohammed, W., Johnson, E., Multimode interference-based fiber-optic displacement sensor (2003) Photonics Technology Letters, IEEE, 15, pp. 1129-1131. , augMohammed, W., Mehta, A., Johnson, E., Wavelength tunable fiber lens based on multimode interference (2004) Lightwave Technology, Journal of, 22, pp. 469-477. , febFrazão, O., Silva, S.O., Viegas, J., Ferreira, L.A., Araújo, F.M., Santos, J.L., Optical fiber refractometry based on multimode interference (2011) Appl. Opt., 50, pp. E184-E188. , SepMohammed, W.S., Smith, P.W.E., Gu, X., All-fiber multimode interference bandpass filter (2006) Opt. Lett., 31, pp. 2547-2549. , SepWang, Q., Farrell, G., Multimode-fiber-based edge filter for optical wavelength measurement application and its design (2006) Microwave and Optical Technology Letters, 48 (5), pp. 900-902Wang, P., Brambilla, G., Ding, M., Semenova, Y., Wu, Q., Farrell, G., High-sensitivity, evanescent field refractometric sensor based on a tapered, multimode fiber interference (2011) Opt. Lett., 36, pp. 2233-2235. , JunFrazão, O., Silva, S.F.O., Guerreiro, A., Santos, J.L., Ferreira, L.A., Araújo, F.M., Strain sensitivity control of fiber bragg grating structures with fused tapers (2007) Appl. Opt., 46 (36), pp. 8578-8582Biazoli, C.R., André, R.M., Frazão, O., Cordeiro, C.M.B., Tapering down optical fiber to ultra-high strain sensitivity (2012) Photonics Technology Letters, IEEE, , Submitte

High-sensitivity temperature sensor based on anti-resonance in high-index polymer coated optical fiber interferometers

Compared to the multimode interference (MMI) effect, the anti-resonance (AR) effect does not rely on the multimode property of the optical waveguide. This Letter shows that fiber bending can suppress the MMI and can break the superposition of AR spectra of multiple modes in a high-index polymer-coated optical fiber interferometer based on a single-mode fiber—polymer-coated no-core fiber—single-mode fiber hetero-structure. This results in the dominance of the AR spectrum of an individual mode and consequently in periodic sharp transmission dips. As a result of this phenomenon and large thermo-optical and thermal expansion coefficients of the polymer, a compact, high-sensitivity and linear response temperature sensor with the sensitivity as high as −3.784nm/∘C has been demonstrated experimentally

Photonic crystal fiber half-taper probe based refractometer

A compact singlemode - photonic crystal fiber - singlemode fiber tip (SPST) refractive index sensor is demonstrated in this paper. A CO2 laser cleaving technique is utilised to provide a clean-cut fiber tip which is then coated by a layer of gold to increase reflection. An average sensitivity of 39.1 nm/RIU and a resolvable index change of 2.56 x 10-4 are obtained experimentally with a ~3.2 µm diameter SPST. The temperature dependence of this fiber optic sensor probe is presented. The proposed SPST refractometer is also significantly less sensitive to temperature and an experimental demonstration of this reduced sensitivity is presented in the paper. Because of its compactness, ease of fabrication, linear response, low temperature dependency, easy connectivity to other fiberized optical components and low cost, this refractometer could find various applications in chemical and biological sensing

Optimized Multimode Interference Fiber Based Refractometer in A Reflective Interrogation Scheme

A fiber based refractometer in a reflective interrogation scheme is investigated and optimized. A thin gold film was deposited on the tip of a coreless fiber section, which is spliced with a single mode fiber. The coreless fiber is a multimode waveguide, and the observed effects are due to multimode interference. To investigate and optimize the structure, the multimode part of the sensor is built with 3 different lengths: 58 mm, 29 mm and 17 mm. We use a broadband light source ranging from 1475 nm to 1650 nm and we test the sensors with liquids of varying refractive indices, from 1.333 to 1.438. Our results show that for a fixed wavelength, the sensor sensitivity is independent of the multimode fiber length, but we observed a sensitivity increase of approximately 0.7 nm/RIU for a one-nanometer increase in wavelength

Simultaneous Measurement for Strain and Temperature Using Fiber Bragg Gratings and Multimode Fibers

An all-fiber sensor capable of simultaneous measurement of temperature and strain is newly presented. The sensing head is formed by a fiber Bragg grating combined with a section of multimode fiber that acts as a Mach-Zehnder interferometer for temperature and strain discrimination. The strain and temperature coefficients of multimode fibers vary with the core sizes and materials. This feature can be used to improve the strain and temperature resolution by suitably choosing the multimode fiber. For a 10 pm wavelength resolution, a resolution of 9.21 μ∈ in strain and 0.26°C in temperature can be achieved

Investigation of a Side-polished Fiber MZI and Its Sensing Performance

A novel all-fiber Mach–Zehnder interferometer (MZI), which consists of lateral core fusion splicing of a short section of side-polished single mode fiber (SMF) between two SMFs was proposed and demonstrated. A simple fiber side-polished platform was built to control the side polished depth through a microscope. The sensitivity of the fiber MZI structure to the surrounding refractive index (RI) can be greatly improved with the increase of the side-polished depth, but has no effect on the temperature sensitivity. The sensor with a polished depth of 44.2 μm measured RI sensitivity up to -118.0 nm/RIU (RI unit) in the RI range from 1.333 to 1.387, which agrees well with simulation results by using the beam propagation method (BPM). In addition, the fiber MZI structure also can achieve simultaneous measurement of both RI and temperature. These results show its potential for use in-line fiber type sensing application

Studies on Temperature and Strain Sensitivities of a Few-mode Critical Wavelength Fiber Optic Sensor

This paper studied the relationship between the temperature/strain wavelength sensitivity of a fiber optic in-line Mach-Zehnder Interferometer (MZI) sensor and the wavelength separation of the measured wavelength to the critical wavelength (CWL) in a CWL-existed interference spectrum formed by interference between LP01 and LP02 modes. The in-line MZI fiber optic sensor has been constructed by splicing a section of specially designed few-mode fiber (FMF), which support LP01 and LP02 modes propagating in the fiber, between two pieces of single mode fiber. The propagation constant difference, Δβ, between the LP01 and LP02 modes, changes non-monotonously with wavelength and reaches a maximum at the CWL. As a result, in sensor operation, peaks on the different sides of the CWL then shift in opposite directions, and the associated temperature/strain sensitivities increase significantly when the measured wavelength points become close to the CWL, from both sides of the CWL. A theoretical analysis carried out has predicted that with this specified FMF sensor approach, the temperature/strain wavelength sensitivities are governed by the wavelength difference between the measured wavelength and the CWL. This conclusion was seen to agree well with the experimental results obtained. Combining the wavelength shifts of the peaks and the CWL in the transmission spectrum of the SFS structure, this study has shown that this approach forms the basis of effective designs of high sensitivity sensors for multi-parameter detection and offering a large measurement range to satisfy the requirements needed for better industrial measurements

Core-Offset Small-Core-Diameter Dispersion Compensation Fiber Interferometer and its Applications in Fiber Sensors

We propose a core-offset small core diameter dispersion compensation fiber (DCF) interferometer and investigate its applications in fiber sensors. If the transverse force is applied to a short section of the DCF, there is almost no crosstalk on the transmission spectrum between the extinction ratio variation induced by the transverse force and the wavelength shift caused by the longitudinal strain or ambient temperature, which can be applied to measure both transverse and longitudinal strain, or both transverse strain and temperature, simultaneously. The proposed sensors have the advantages of low cost, simple and compact structure, and good reproducibility