Evanescent wave fiber optic biosensors are a subset of fiber optic biosensors that perform the sensing function along the fibers cylindrical length. A simple theory for interpreting these results has been developed. Osa power density of the evanescent field in the vicinity. This optical fiber has a hollow structure and an inner core in the cave. Evaluation of an evanescent fiber optic chemical sensor for.
Fiber evanescent field technology fiber optic products. To say it simply, the higher vs value is, the deeper the penetration in the evanescent field is. Optical fiber evanescent field components an overlooked. Other fiber devices, such as the 968p polarization splitter andor 915b 916b piezo fiberstretchers, can be integrated with coupler arrays to form advanced communications systems and fiber interferometers. The optical responses show that the output intensity of the ag nanoparticlemodified sensor is enhanced as the evanescent wave excites the local surface plasma resonance. Three fiber bragg gratings were used to measure the changes in evanescent field. Here, we present an evanescent fieldbased device capable of confining low index nanoscale particles using modest optical powers as low as 1. Tapering not 7 only exposes the evanescent field to the surroundings, but also increases the evanescent field magnitude and penetration depth 8, 9. Rp photonics encyclopedia near field and far field. Find out inside pcmag s comprehensive tech and computerrelated encyclopedia. It is also possible to sharpen the fiber by heating it up to its softening temperature and then by stretching it 14. Polymer optical fiber for terahertz low loss propagation and high evanescent field. Theoretical analysis of fiberoptic evanescent wave sensors.
In electromagnetics, an evanescent field, or evanescent wave, is an oscillating electric andor magnetic field which does not propagate as an electromagnetic wave. The device consisted of three fiber optic evanescent filed sensors which were fabricated by tapered single mode fibers and immersed in liquid. Pdf a large penetration depth of an evanescent wave is the key to success for developing a fiberoptic evanescentwave sensors. Singlemode optical fibers are finding increased uses in areas such as long haul communications, local area networks, environmental sensing and optical signal processing. Phoenix photonics fiber evanescent field technology technical briefing phoenix photonics 2003 evanescent field v1.
Blair environmental characterizations and monitoring systems department sandia national laboratories p. The sensing platform not only provides a highly effective and versatile evanescent field ef based probe, but also possesses three orders of magnitude higher sensing signal collection ability than that of microscopic systems. For instance, in a scanning near field microscope bohn et al. We proposed a new approach to attitude measurement by an evanescent field based optical fiber sensing device and demonstrated a liquid pendulum. A silver nanoparticlemodified evanescent field optical. Evanescent fieldmodulated magnetic immune sensor based on. Osa evanescent field refractometry in planar optical fiber. Evaluation of an evanescent fiber optic chemical sensor for monitoring aqueous volatile organic compounds dianna s. The evanescent field is the portion of the guided mode found outside the core region of an optical fiber. In fiber optics, the evanescent field may be used to provide coupling to another fiber.
The platform is mechanically robust, and can survive elevated temperatures approaching c and exposure to common solvents, including acetone, gasoline, and. In evanescent wave fibre optic sensors, the interrogating light remains guided in the sensor and no coupling optics are required at the sensing region. Evanescent field in the corecladding interface of an optical fiber. Access to this field is obtained using a grinding and polishing technique to remove a section of the fiber cladding. The nanofiber optic evanescent field sensor based on a changed cladding part as a sensor presented numerically. 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. Nanopatterned evanescentfield fiberoptic interferometer as. The role of evanescent field in optical fiber sensing. The evanescent tail is an integral part of the guided wave and its characteristics are. Fiber optic sensors fundamentals and applications, fourth edition, 2014 available at. Evanescent field optical fiber sensors of high sensitivity are obtained by embellishing the surface of the sensing fibers with biochemical reagents or films sensitive to the analyte. Evanescent wave absorption sensor with directgrowth mos2. Evanescent field dictionary definition evanescent field. The influences of numerical opening, core radius of the fiber, the wavelength is effected on the light source and the submicron fiber on the sensors are promise to studied in this work.
Evanescent wave coupling plays a major role in the theoretical explanation of extraordinary optical transmission. The unique advantage of the technology is survivability in harsh environments. Photonic sensing has always encountered problems such as enhancements of lightanalyte interaction and signal collection efficiency. See fiber optics glossary explanation of evanescent field. The influences of numerical aperture, core radius of the fiber and the taper ratio on the sensitivity of the sensor are investigated. A nanotaper optical fiber coated with an ultrathin palladium film is used to detect low concentrations of hydrogen with fast response time. Power density of the evanescent field in the vicinity of a tapered fiber. Banshi dhar gupta, chandra deep singh, and anurag sharma fiber optic evanescent field absorption sensor. Evanescent coupling, as near field interaction, is one of the concerns in electromagnetic compatibility. The launching condition and the geometry of the sensing region are found to be the main parameters that can influence the sensitivity of the sensor. Ideally, the fiber fibers will conduct light in the uvvis, mir and fir as well. A silver nanoparticlemodified evanescent field optical fiber.
For a rough criterion, one can calculate the rayleigh length based on the mode radius of the fundamental fiber mode. Waveguide evanescent field absorption has been measured as a function of cladding refractive index and bulk absorption coefficient. Splicefree pm coupler trees and assemblies are available in custom configurations having very low backreflection and insertion loss. Box 5800 albuquerque, nm 871850755 abstract linear chemometric algorithms were used to model the quantitative response of. In electrical engineering, evanescent waves are found in the near field region within one third of a wavelength of any radio antenna. Nov 16, 2015 highpower graphene modelocked tmho codoped fiber laser with evanescent field interaction. This letter demonstrates a refractometer in integrated optical fiber, a new optical platform that planarizes fiber using flame hydrolysis deposition fhd. We introduced a nanopatterned fiber optic interferometer foi based on an optical fiber line embedded with a short capillary which excites the evanescent field by total reflection of light in the wall waveguide interacting with the fluid and causing the optical signal change. 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. Recently, evanescent field optical sensors have been used in a wide range of applications for their high accuracy, low cost, and rapid detection techniques, which are particularly useful for monitoring environmental samples and toxic. The sensitivity of the silver nanoparticle modified evanescent field optical fiber sensor is higher for the methylene blue solution. 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. A general theory for fiberoptic, evanescentwave spectroscopy and sensors is presented for straight, uncladded, stepindex, multimode fibers.
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. Increase in the numerical aperture of the fiber increases the sensitivity of the sensor in the case of both the probes. Ideally, the fiberfibers will conduct light in the uvvis, mir and fir as well. Fiber optic evanescent wave foew sensors are promising in pollutant detection and evaluation of water quality because of their high resistance to co. Results show that the value of the absorption will reflect the concentration of the concentration of methylene blue in optical fiber. Design of photonic crystal waveguides for evanescent coupling to optical fiber tapers and integration with highq cavities. The expressions for the effective evanescent absorption coefficient of the fluid have been derived for a diffuse source as well as a collimated sourcemicroscope objective combination. Mar 27, 2017 in electromagnetics, an evanescent field, or evanescent wave, is an oscillating electric andor magnetic field which does not propagate as an electromagnetic wave but whose energy is spatially. The power density in the vicinity of a tapered fiber is calculated, with the vectorial model of stepindex circular waveguides. A comparative experimental study of the fiber optic evanescent field absorption sensor based on straight and ushaped probes is presented. Fiber optic evanescent field absorption sensor based on a. Evanescent field article about evanescent field by the. For the fundamental he11 mode carrying a power of 1 watt, we show that it is possible to obtain theoretical densities in the range of 108 wcm2 at the fiber surface.
Manipulation of the optical signal by components in fiber networks is generally accomplished by breaking the fiber path and applying the required functionality in an alternative media, either planar waveguide or free space. Long path fiberoptic sensor for evanescent field absorbance. The typical output of the fiber laser optical spectrum. An optical fiberwaveguidefiber platform for ppt level. Evanescent field modulated magnetic immune sensor based on magnetic fluid and polymer optical fiber abstract. Fiber optic evanescent wave absorptionbased sensors. Specifically, efocs can use commercially available plastic clad silica, pcs, fiber optic cables as the optical waveguide element. Evanescent field enhancement in liquid crystal optical. This thesis explores using the evanescent field of an optical fiber to construct several different devices. Optical fiber an optical fiber is made up of the core carrying the light pulses, the cladding reflecting the light pulses back into the core and the buffer coating protecting the core and. To meet the guiding conditions for an electromagnetic wave propagating in a dielectric waveguide the field decays exponentially away from the corecladding boundary. Characterization of a fiberoptic evanescent wave absorbance sensor for nonpolar organic compounds j. Evanescent wave article about evanescent wave by the free.
In this part we will present a method of intensity modulation based on direct interaction of the measurand with the electromagnetic wave. Evanescent wave opticalfiber sensing temperature, relative. See fiber optics glossary explanation of evanescent wave. In this article, an evanescent field absorption sensor based on special u shaped optical fiber is proposed. In an optical fiber, the light that passes from the core into the cladding. B 2011 22742284 2003 shaping the evanescent field of optical. The effects of numerical aperture and the core radius of the fiber on the sensitivity of the sensor are experimentally investigated. Ache kernforschungszentrum karlsruhe, institut fur radiochemie, postfaeh 3640, d7500 karlsruhe 1, germany a fiber optic evanescent field absorbance sensor efas is described. Evanescent field article about evanescent field by the free. Due to the extreme vicinity of the 2d photodetector with the fiber core, the device can effectively couple with the evanescent field and accurately detect information transmitted inside the optical fiber. The relationship of the scanning principle to the lukosz concept is rather obvious. Fiber evanescent field technology phoenix photonics. Optical waveguide theory georgia institute of technology.
Temporary or semipermanent connections are made by means of specialized optical fiber connectors. Theory of fiberoptic, evanescentwave spectroscopy and. The easiest configuration of this sensor is shown on figure 3b, where the protective plastic jacket of the fiber has been removed and the cladding has been reduced by polishing or by chemical attacks. Optical fiber evanescent field components an overlooked technology. An optical fiber waveguide fiber platform for ppt level evanescent field based sensing. Coupling of optical fibers without loss for fiber tapping. Evanescent wave article about evanescent wave by the. Evanescent field dictionary definition evanescent field defined.
The evanescent field can be used to develop optical fiber sensors and can be applied to the performance of absorption measurements. The platform is mechanically robust, can survive elevated temperatures approaching oc and exposure to common solvents, including acetone, gasoline and. For demonstration, we transferred a complete 2d multilayer inse photodetector device onto a stripped optical fiber. Evanescent field refractometry in planar optical fiber. Fiberoptic evanescentfield sensor for attitude measurement. Evanescent field devices using singlemode optical fibers. Download scientific diagram evanescent field in the corecladding interface of an optical fiber from publication. Products splicefree pm coupler trees and assemblies are available in custom configurations having very low backreflection and insertion loss. The evanescent field optical sensor is an excellent promising candidate for labelfree optical fiber sensing. Simple equation to estimate the output power of an evanescent field absorptionbased fiber sensor. In a waveguide, a timevarying field having an amplitude that decreases monotonically as a function of transverse radial distance from the waveguide, but without an accompanying phase shift. To meet the guiding conditions for an electromagnetic wave propagating in a dielectric waveguide the field.
An optical fiber is a flexible, transparent fiber made by drawing glass or plastic to a diameter slightly thicker than that of a human hair. The promising use of such intense evanescent fields as atomic mirrors is considered, and the. Evanescent wave coupling is used in powering devices wirelessly. As these systems become more complex there is a growing need for efficient lowloss optical fiber components. Evaluation of an evanescent fiber optic chemical sensor. 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. The results pointed out the sensitivity of the sensor increases when the numerical. In an optical fiber, the light that passes from the core into the. 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. Our small footprint couplers, splittercombiners and other components can be configured as nxm port, splice free coupler arrays and.
Highpower graphene modelocked tmho codoped fiber laser. Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber optic communications, where they permit transmission over longer distances and at higher bandwidths data rates than electrical. An experimental study of the fiber optic evanescent field absorption sensor based on tapered sensing probe is presented. Evanescent field enhancement in liquid crystal optical fibers. Evanescent wave definition of evanescent wave by medical. Rp photonics encyclopedia near field and far field, dipole. In this study, we propose an optical fiber waveguide fiber ofwf sensing platform, which comprises a noncladded polymer waveguide sandwiched by two multimode optical fibers coaxially fabricated by laserinduced selfwritten waveguide lisw technique. Apr 30, 2010 optical fiber an optical fiber is made up of the core carrying the light pulses, the cladding reflecting the light pulses back into the core and the buffer coating protecting the core and. The near field for light exiting an optical fiber is the area in which the field profile has not yet been substantially expanded.
In a waveguide, such as an optical fiber or a slab dielectric waveguide, a timevarying transverse electromagnetic field that a has an amplitude that decreases monotonically as a function of transverse distance, i. Choudhury 1 1 institute of microengineering and nanoelectronics imen, universiti kebangsaan malaysia ukm, 43600 bangi, selangor, malaysia. A large penetration depth of an evanescent wave is the key to success for developing a fiberoptic evanescentwave sensors. 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.
The methylene blue is absorbed into the optical fiber and the absorbance is tested. To meet the guiding conditions for an electromagnetic wave propagating in a dielectric. Evanescent wave fiber optic biosensors sciencedirect. In order to increase the interaction with the evanescent field, it is possible to use special fibers, like dfibers or microstructured fibers. A comparative study of the fiber optic evanescent field absorption sensors based on parabolic, linear, and exponentiallinear taper profiles has been carried out. Splicefree pm coupler trees and assemblies are available in custom configurations having very low backreflection and insertion loss 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. Tir, consists of an optical phenomenon that occurs when a light beam hits the interface between two media with an angle greater than the critical. 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. Temperature effects on a fiberoptic evanescent wave. In electrical engineering, evanescent waves are found in the nearfield region within one third of a wavelength of any radio antenna. This work demonstrates a refractometer in integrated optical fiber iof, a new optical platform that planarizes fiber using flame hydrolysis deposition fhd. Nanooptical fiber evanescent field sensors scientific.
Many types of optical fiber hydrogen sensors have been proposed, including evanescent wave absorption devices 9,10, micromirror optode 11,12, machzehnder interferometers, surface plasmon resonance spr devices 14, and fiber bragg gratings fbg 1517. One end of the fiber is polished to form an angledtip, whereas the. Evanescent field in optical fiber sensing pyroistech. Pdf theoretical analysis of fiberoptic evanescent wave sensors. The field of applied science and engineering concerned with the design and application of optical fibers is. A highly sensitive and simple design of intensity based magnetic field sensor is proposed and experimentally demonstrated with a safe data transformation by employing optical fiber as a magnetic resonancecompatible sensor. Sensitive and versatile evanescent wavesensing systems featuring polished optical fiberbased sensor designs with lowcost light sources have been develop. Optical detection of toluene in water using an igi optical fiber with a short sensing region. A fiber optic sensor with double pass evanescent field absorption from an unclad ubent multimode optical fiber is presented. Fiber optic evanescent wave absorption sensors based on four different designs are described.
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