An evanescent wave is a nearfield wave with an intensity that exhibits exponential decay without absorption as a function of the distance from. A long distance, distributed gas sensing using the micronano fiber evanescent wave few quartz enhanced photoacoustic spectroscopy technique was demonstrated. Evanescent wave fiber optic biosensors are a subset of fiber optic biosensors that perform the sensing function along the fiber s cylindrical length. Evanescent wave opticalfiber sensing temperature, relative. Evanescent wave scattering ews in the psgs coating. Optical characteristics of fiber optic evanescent wave sensors. An automated optical biosensor system based on fluorescence excitation and detection in the evanescent field of a quartz fiber was used to detect 16mer oligonucleotides in dna hybridization assays.
Gold nanoparticle amplified optical microfiber evanescent. The evanescent wave from an optical fiber can be used in a gas sensor, and evanescent waves figure in the infrared spectroscopy technique known as attenuated total reflectance. We report a fiber optic relative humidity rh sensor based on the evanescent wave absorption spectroscopy using a single ubend plasticclad silica fiber with high dynamic range and high sensitivity. The experimental setup used to produce fizeau fringes in transmission is shown in fig.
In particular, foew sensors have proven very useful for online detection and monitoring of multiple parameters in water. The coupler comprises a pair of substrates, each substrate having an optically worked fiber embedded therein and wherein the substrates are secured together such that the optical fibers are in optical. The effect of the cladding refractive index on an optical fiber evanescentwave sensor. The size of the interphase can vary significantly, d epending on the exact nature of the fiber surface treatment and its interaction with the surrounding resin matrix. Thus the sample poured in is in direct contact with the evanescent wave. Model of a fiberoptic evanescentwave fluorescence sensor nist. Fiber optic evanescent wave foew sensors are promising in pollutant detection and evaluation of water quality because of their high resistance to corrosion, smart structure, antielectromagnetic interference, and low cost. Previous modal functions and experimental results describing the variation of optical constants of human blood with different hemoglobin concentrations in the nearinfrared spectral region are. Evanescent wave absorption based fiberoptic sensor springerlink.
Evanescent wavecoupled dye laser emission in optical fibers. Fiberoptic evanescent wave foew sensors, which are composed of silica and polymer optical fibers 1,2, are widely applied in chemistry 3, biochemistry 4, life sciences 5, and environmental research 6 because they provide fast and reliable results in terms of measuring solution concentrations, chemical component analysis, and obtaining the absorption spectra of. Dec 01, 2002 microbent optical fibers are potential candidates for evanescent wave sensing. Fiber optic tapers are important devices that can act as sensors and couplers. Us4688882a optical contact evanescent wave fiber optic. Consequently, due to the unique property of tfi technique it has been used to study the radial dispersion of evanescent wave constants in bent singlemode optical fiber. In recent years, optical fiber evanescent wave absorption ewa sensors have received a lot of attentions, which are based on the interaction between analyte and evanescent field of light traversing in optical fiber 1. To test silica optical fibers as evanescent wave sensors the procedures described below for fiber preparation and performing adsorption experiments were followed. Evanescent waves can transfer energy between waveguides. Gas molecules that exhibit characteristic vibrational absorption lines in the nearir region that correspond to the transmission window for.
This system provides a physical basis for fiber optic fluoroimmunoassay independent of immunochemical binding and kinetics. The analyte diffuses into the hydrophobic cladding. The sensor, composed of a lead salt tunable infrared laser and a multimode uncladded silver halide infrared optic fiber, was used for rapid measurement of sulfur hexafluoride pressures at a fewpercent detection limit. Fiber optic evanescent wave spectroscopy in the middle infrared introduction s pectroscopy in the middle in frared mir in the spectral range 3 30 m is a powerful tool for qualitative and quantitative analyses of materials in the gas, liquid, or solid phases.
In the first part of the present work, attention is given to the fundamental characterisics of wave propagation in radially inhomogeneous single mode fibers, with emphasis on optical fibers having a parabolic index profile or one with a dip in a fiber axis. Graphene based chalcogenide fiberoptic evanescent wave. The cladding defines with the core an optical waveguide providing. A biotinylated capture probe was immobilized on the fiber surface via avidin or streptavidin. Temperatureindependent polymer optical fiber evanescent wave.
Microbent optical fibers are potential candidates for evanescent wave sensing. The excitation of fluorescein by evanescent wave interaction and subsequent detection of fluorescence from the optical fiber endface by the reciprocal process was studied. Our small footprint couplers, splittercombiners and other components can be configured as nxm port, splice free coupler arrays and as custom assemblies fabricated for high er and low loss. To a simple first look, the wave just hits the surface, say a wall, turns around, and comes back. Furthermore, the optical crosssection of gnps also should be optimized to enhance their interaction with the evanescent field. May 24, 2018 waves sometimes reflect off of surfaces. An evanescent field or evanescent wave is a nearfield standing wave with an intensity that shows an exponential decay with the distance to. Total internal reflection tir is the optical phenomenon in which the surface of the water in a fishtank for example when viewed from below the water level, reflects the underwater scene like a mirror, with no loss of brightness fig. Pdf theoretical analysis of fiberoptic evanescent wave sensors.
The optical fiber ewa sensors possess high sensitivity and are more sensitive than. In an evanescent wave fibre optic sensor, the cladding of the optical fibre is removed and it is placed in direct contact with the sample. Dec 01, 2014 an evanescent wave is a nearfield wave with an intensity that exhibits exponential decay without absorption as a function of the distance from the boundary at which the wave was formed. Theory of fiberoptic, evanescentwave spectroscopy and sensors. Fiber optic evanescent wave sensor with graphene as an absorptionenhancing layer to measure hemoglobin concentration in human blood is proposed. A coiled fiberoptic chemical sensor has proven to be effective for the remote detection of volatile organic compounds, such as trichloroethylene tce, 1,1dichloroethylene dce, and gasoline, in aqueous solutions. A general analysis for evanescent wave transmission using a singlemode optical fiber was presented on the basis of optical waveguide theory. Evanescent waves international school of photonics research. Fiber evanescent field technology phoenix photonics. This is achieved by removing a certain region of 24. Evanescentwave in perturbed optical fibers sciencedirect. In electrical engineering, evanescent waves are found in the nearfield region within one third of a wavelength of any radio antenna. Other fiber devices, such as the 968p polarization splitter andor 915b916b piezo fiber stretchers, can be integrated with coupler arrays to form advanced communications systems and fiber interferometers. Thus, ultrathin omfs should be used to achieve high sensitivity.
Optical fibers have been widely used as sensing devices because they offer immunity to electromagnetic interference as well as offering electrical insulation, resistance to corrosion, low cost and other advantages. Evanescent wave fiber optic biosensors sciencedirect. A fiber optic cure sensor based on evanescent wave fluorescence spectroscopy has been designed to probe the interphase region of glassreinforced composites. Infrared transparent optical fibers as evanescent wave sensors. Sensors 2009, 9 10424 optical glass fibers have been studied to obtain high sensitivity devices such as chemical sensors 1,2. Analysis of evanescent wave transmission on singlemode.
Fiberoptic evanescent wave spectroscopy in the middle infrared. Optical fiber humidity sensor based on evanescent wave scattering pages in study. Sensitive and versatile evanescent wavesensing systems featuring polished optical fiberbased sensor designs with lowcost light sources have been develop. Theory of fiberoptic, evanescentwave spectroscopy and. Fiber optic evanescent wave foew sensors, which are composed of silica and polymer optical fibers 1,2, are widely applied in chemistry 3, biochemistry 4, life sciences 5, and environmental research 6 because they provide fast and reliable results in terms of measuring solution concentrations, chemical component analysis, and obtaining the absorption spectra of chemicals of interest during. The hybridization with fluoresceinlabeled complementary strands was.
Light propagating through an optical fiber consists of two components. People frequently resort to putting a thiner or larger layer on the cladding, because as its optical characteristics vary depending on the substance to detect, the evanescent wave will also be affected. Perfluorinated plastic optical fiber tapers for evanescent. Microbent optical fibers as evanescent wave sensors. Electromagnetic waves propagate within an optical fiber by total internal reflection at the exposed surface. We investigate the behavior of a permanently microbent fiber optic sensor when it is immersed in an absorbing medium. Evanescent wave absorption ewa based fiberoptic sensors have found widespread applications ranging from environmental sensing to biosensing. Highprecision detection and identification of a large variety of gases are possible. Evanescent wave coupling is used to excite, for example, dielectric microsphere resonators. A process to produce randomhole optical fibers was recently developed that uses a novel in situ bubble formation technique.
Evaluation of an evanescent fiber optic chemical sensor for. Evanescent wave article about evanescent wave by the free. Temperature effects on a fiberoptic evanescent wave. Evanescent wave definition of evanescent wave by medical.
Temperatureindependent polymer optical fiber evanescent. It is also possible to sharpen the fiber by heating it up to its softening temperature and then by stretching it 14. A surfacesensitive measurement technique, evanescent wave sensing, has been applied to resincure monitoring of graphite fiber polyimide composites by employing infrared transmitting optical fiber sensors. Pdf a large penetration depth of an evanescent wave is the key to success for developing a fiberoptic evanescentwave sensors. Optical fiber sensors based on the evanescent wave phenomenon have received considerable attention due to the ability of the evanescent wave to. Evanescent wave article about evanescent wave by the. Fiberoptic evanescent wave biosensor for the detection of. The effect of the cladding refractive index on an optical fiber. Research on development of optical gas sensors based on evanescent wave absorption in randomhole optical fibers is described. The main feature of fiber tapers is the fact that they can strongly enhance the power fraction in the cladding in the form of evanescent wave increasing the sensitivity to environmental changes. Two distinct detection schemes, namely, brightfield and darkfield detection configuration, are employed for the measurements. The work herein contained describes the fabrication of three types of.
Such a sensor scheme has the advantages of higher detection sensitivity, distributed gas sensing ability, lower cost, and a simpler fabrication procedure compared to conventional few gas sensors using a photonic crystal fiber or a. Sensors based on this principal, known as evanescent fiber optic chemical sensors, efocs, or fiber optic evanescent wave sensors, fews, hold promise for use in environmental applications. Evanescent wave fiberoptical biosensor utilizes the principles of attenuated total reflection atr spectroscopy to detect and measure the interactions of biochemical materials instantaneously. Optical characteristics of fiberoptic evanescent wave sensors. The optical waveguide comprises a core and a cladding having a cladding refractive index lower than that of the core for guiding light to be propagated in the optical waveguide. Modeling of evanescent wave optical fiber biosensor. Evanescent wave coupling is commonly used in photonic and nanophotonic devices as waveguide sensors or couplers see e. Fiber evanescent field technology fiber optic products. Sensitive and versatile evanescent wave sensing systems featuring polished optical fiber based sensor designs with lowcost light sources have been developed for temperature, relative humidity, and ph measurements. In particular, uncladded glass fiber tapers have been used for evanescent absorption measurements and. In this part we will present a method of intensity modulation based on direct interaction of the measurand with the electromagnetic wave. This monograph strongly related only about optoelectronic biosensor, in which discussed investigated evanescent wave optical fiber biosensor is one of the strong light carry biological information sensation and high speed detection sensor. Apr 14, 2017 this video gives a brief introduction to evanescent waves which arise at the interface of two media when light travels from one to another and is reflected b.
Splicefree pm coupler trees and assemblies are available in custom configurations having very low backreflection and insertion loss. Etched optical fiber for measuring concentration and. Mar 09, 2011 this monograph strongly related only about optoelectronic biosensor, in which discussed investigated evanescent wave optical fiber biosensor is one of the strong light carry biological information sensation and high speed detection sensor. The availability of lowloss optical fibers with the associated benefits of freedom from electromagnetic interference, small size, light weight, and wide bandwidth. A novel fiber optic evanescent wave sensor is presented. There is provided an evanescent wave multimode optical waveguide sensitive to a chemical species or to a physical parameter. Evanescent field in optical fiber sensing pyroistech. Such a sensor scheme has the advantages of higher detection sensitivity, distributed gas sensing ability, lower cost, and a simpler fabrication procedure compared to conventional few gas sensors using a. The hybridization with fluoresceinlabeled complementary strands was monitored in real time by. But, when you look closer, the wall still gets affected.
Osa randomhole optical fiber evanescentwave gas sensing. To meet the guiding conditions for an electromagnetic wave propagating in a dielectric. In this post we will briefly go through a theoretical introduction of evanescent field associated to optical fiber sensors and its applications to perform absorption measurements. Evanescent wave absorption sensor with directgrowth mos2. Recent advances in fiberoptic evanescent wave sensors for. Specifically, efocs can use commercially available plastic clad silica, pcs, fiber optic cables as the optical waveguide element. Long distance, distributed gas sensing based on micronano. A general theory for fiberoptic, evanescentwave spectroscopy and sensors is presented for straight, uncladded, stepindex, multimode fibers.
The second part considers the transmission properties of optical fiber couplers, in the cases of 1 a bundle of fibers symmetrically. For an absorbing medium surrounding the optical fiber. Evanescent wave evanescent wave penetrates less than a wavelength beyond the core excites the fluorescent molecules penetration depth dp. Evanescent wave dye laser emission is observed in an optical fiber when it is surrounded by a gain medium excited dye molecules of lower refractive index. Abstractusing the evanescentwave saturation effect of hydrogenfree lowtemperature synthesized fewlayer graphene covered on the cladding region of a sidepolished singlemode fiber, a blue pumpinfrared probebased alloptical switch is demonstrated with specific wavelengthdependent probe modulation efficiency. The capability of optical fibres to function as sensors is usually attributed to operation by excitation of fluorescence using an evanescent wave, which will exist when the refractive index of the waveguide is greater than the refractive index of the coating of organic material. Saturated evanescentwave absorption of fewlayer graphene. A single mode, evanescent wave, fiber optic coupler. Guided light waves that extend beyond the boundary of a fiber core into the cladding. The role of evanescent field in optical fiber sensing. In evanescent wave fibre optic sensors, the interrogating light remains guided in the sensor and no coupling optics are required at the sensing region. Light guided in the inner part of an optical fibers cladding rather than in the core, i. Evanescent wave fobs are biosensors that utilize evanescent wave detection techniques. Phoenix photonics fiber evanescent field technology technical briefing phoenix photonics 2003 evanescent field v1.
292 1477 98 550 1011 456 950 430 1087 1263 489 1163 1135 727 49 1147 1541 789 447 151 342 879 156 1057 1465 1056 635 1420 755 1422 150 69 309 1062 417 48 931 692