Evanescent field spectroscopy efs using optical waveguides, both conventional 1 and structured 2 is an extremely powerful tool, both in terms of chemical sensor applications and as well as fundamental molecular studies of layers and films that circumvents the need for. The sensor, comprised of a single led source and a claddingfree multimode fiber, operates on the principle of evanescent field and differential spectroscopy. The overtone spectra derive from midinfrared resonances that provide a signature of analyte toxicity. Electrochemical optical waveguide lightmode spectroscopy. Refractometry using evanescent field based fiber loop. Evanescent field spectroscopy using structured optical fibers. Pdf evanescent wave absorption spectroscopy by means of bi. View the article pdf and any associated supplements and figures for a period of 48 hours. The red and blue solid curves indicate the variation of field strength of the evanescent wave generated by point a go through the superlens with k. Optical evanescent wave methods for the study of biomolecular interactions volume 29 issue 1 peter b. Experiments of microwave spectroscopy with cavity spectrometers utilizing the evanescent field extending outside dielectric resonatos. Penetrationdepth characteristics of evanescent fields at.
Crossley,2 1interdisciplinary photonics laboratories ipl, school of chemistry, 222 madsen building f09, university of. The penetration depth, d p, is a function of the glass index as well as of the wavelength of the propagating light, according to eq. Enhanced evanescent field spectroscopy at waveguide. We performed an optogalvanic spectroscopy experiment with the evanescent light to observe resonances from atoms located very close to the surface. Evanescent wave coupling is commonly used in photonic and nanophotonic devices as waveguide sensors or couplers see e.
Integrated plasmonenhanced raman scattering i pers. Theory of fiberoptic, evanescentwave spectroscopy and. Evanescent wave article about evanescent wave by the free. Evaluation of an evanescent fiber optic chemical sensor for. Mar 01, 2015 side polished fiber as an evanescent field based sensor element has been fabricated with a low insertion loss of 0. We propose and demonstrate, through simulation and experiment, how the interaction of an optical field within a waveguide designed for chemical sensing and, more generally, evanescent field spectroscopy can be enhanced substantially by strategic deposition of high index surface layers. Sensors free fulltext toward the required detection. Chemical sensor for monitoring aqueous volatile organic compounds dianna s. Near field scanning optical microscopy nsom or scanning near field optical microscopy snom is a microscopy technique for nanostructure investigation that breaks the far field resolution limit by exploiting the properties of evanescent waves. Localized and propagating surface plasmon coenhanced raman spectroscopy based on evanescent field excitation yu liu, shuping xu, haibo li, xiaoguang jian, weiqing xu state key laboratory of supramolecular structure and materials, jilin university, changchun 012, p. The most effective coupling of the localized and propagating surface plasmons resulted in a 50 times enhanced signal relative to signals obtained on vacuumdepo surface enhanced raman spectroscopy. Evanescent wave article about evanescent wave by the.
Evanescent field absorption sensing using sapphire fibers michael grossman abstract this thesis explores the application of coiled sapphire multimode optical bers for evanescent wave chemical sensing in both the visible spectrum and the near infrared. Results are reported, indicating the advantages ad the possible applications of the new technique. Integrated plasmonenhanced raman scattering ipers spectroscopy. I recently had the opportunity to reexamine the foundations of atr spectroscopy and was surprised to have had to change my own mental picture of the evanescent wave that i. Parriaux singlemode fiber evanescent wave spectroscopy, proc. I recently had the opportunity to reexamine the foundations of atr spectroscopy and was surprised to have had to change my own mental picture of the evanescent wave that i have built over the last 25 years. Pdf theory of fiberoptic, evanescentwave spectroscopy and. Evanescent wave absorption spectroscopy using multimode. Evanescentfield spectroscopy using structured optical fibers. In 20, shiraga et al presented a method to determine the complex dielectric constant of a cell. Integrated waveguide with microfluidic interface for evanescent field absorption spectroscopy has been demonstrated with chalcogenide 2 and su8 3 waveguides. An allfiber singlemode spectroscopic sensor has been realised.
Therefore, many groups conducted biomedical researches based on atr spectroscopy. Electrochemical optical waveguide lightmode spectroscopy ec. Simple evanescent field sensor for nir spectroscopy simple evanescent field sensor for nir spectroscopy nearinfrared nir spectroscopy is a powerful tool for chemical analysis in applications ranging from biomedicine to analysis of food products and textiles 1. A new technique for ir spectroscopic measure merits of liquids, pastes and thin films is reported. Side polished fiber as an evanescent field based sensor element has been fabricated with a low insertion loss of 0. Surface plasmon field enhanced fluorescence spectroscopy spfs utilizes the evanescent electromagnetic field of a surface plasmon to excite chromophors in close proximity to the surface. Osa waveguide evanescent field spectroscopy of trace gases. Evanescent field in surface plasmon resonance and surface.
Evanescent waves play a growing role in many different areas such as guided optics, opticalfiber couplers, integrated optical elements, internal reflection spectroscopy, atom optics, darkfield microscopy, scanning tunneling optical microscopy, microaperture microscopy. Pdf this paper discusses the theoretical and experimental implications of tapering a multimode optical fiber with a view to its use in. Wilkin son optoelectronics research centre, univers ity of southampton, southampton, uk. The effect of the surface, where the evanescent wave is generated by total internal reflection, on the scattering and extinction spectra is investigated via numerical field calculations employing the multiple multipole method. Incident angledependent sers spectra were measured in the.
Nearfield spectroscopy of single molecules at room temperature. Infrared spectroscopy is performed in this format when the sample to be examined is highly absorbing. Localized and propagating surface plasmon coenhanced raman. Evanescent wave spectroscopy when a light beam undergoes total internal reflection, the electromagnetic field is high on one side of the interface and close to zero on the other side. Mar 18, 2004 the highly sensitive nature of surface plasmon resonance spr spectroscopy and surface plasmon field enhanced fluorescence spectroscopy spfs are governed by the strong surface plasmon resonancegenerated evanescent field at the metaldielectric interface. Schematic of experimental setup for excitation and detection of evanescent. Evanescent coupling, as near field interaction, is one of the concerns in electromagnetic compatibility.
Simple evanescent field sensor for nir spectroscopy eprints. Cladding of plastic clad silica fiber is replaced with polymethyl methacrylate doped with ph sensitive. Evanescent absorbance values for methylene blue in a concentration range 3. Infrared spectroscopy is performed in this format when the sample to be examined is. Evanescent wave spectroscopy of number of charges because of the difference between the ionisation crosssections. Pdf a general theory for fiberoptic, evanescentwave spectroscopy and sensors is presented for straight, uncladded, stepindex, multimode fibers. This metrology system uses evanescent field based photoacoustics efpa, a field of research based upon the interaction of an evanescent field with the photoacoustic effect. Evanescent field ir spectroscopy using optical fibres and tunable. The wcspr configuration is a fivephase kretschmann resonance setup composed of a k9 prisminner ag filmmgf2 filmouter ag filmwater structure.
Surface plasmon fieldenhanced raman scattering based on. Evanescentwave infrared spectroscopy with flattened fibers. We detect trace gases at ppb levels using evanescentfield absorption spectroscopy in microring resonators coated with sorbent polymers. Chen 1 institute of microelectronics, astar agency for science, technology and research, singapore and 2 microelecronics center, school of eee, nanyang technological university. We propose a bimetallic waveguidecoupled surface plasmon resonance wcspr configuration to enhance raman scattering with an evanescent field excited using surface plasmons. Analysis of diffusion in polymers using evanescent field spectroscopy. Nearfield scanning optical microscopy nsom or scanning nearfield optical microscopy snom is a microscopy technique for nanostructure investigation that breaks the far field resolution limit by exploiting the properties of evanescent waves. The greatest evanescent field amplitude at the interface and the maximum attenuation of the reflectance are observed when a nonabsorbing. Surface plasmon fieldenhanced fluorescence spectroscopy. Analysis of diffusion in polymers using evanescent field spectroscopy gregory t. A general theory for fiberoptic, evanescentwave spectroscopy and sensors is presented for straight, uncladded, stepindex, multimode fibers. This applies, for example, to morphological resonances of dielectric particles with size parameters 1. In snom, the excitation laser light is focused through an aperture with a diameter smaller than. Evanescent field absorption sensing using sapphire fibers by michael grossman a thesis submitted in partial ful llment of the requirements for the degree of master of science in physics department of physics college of arts and sciences university of south florida major professor.
Theory of fiberoptic, evanescentwave spectroscopy and sensors. Simple evanescent field sensor for nir spectroscopy alina karabchevsky, ping hua and james s. These layers draw out the optical field in the vicinity of probing and take advantage of field localisation. The evanescent wave extends into and interacts with the sample 27, leading to the high sensitivity detection for the few sample. In situ monitoring of ph level with fiber optic evanescent. Pdf simple evanescent field sensor for nir spectroscopy. Evanescent field spectroscopy with optical fibers for. Weis rm, balakrishnan k, smith b, mcconnell hm 1982 stimulation of fluorescence in a small contact region between rat basophil leukemia cells and planar lipid.
With such a small optical penetration depth, the evanescent field is able to interact with the environment very close to the interface of the two materials. Ir absorption spectra of methanol, ethanol, isopropa nol, acetone, ethanoic acid, water, hexane, and. The highly sensitive nature of surface plasmon resonance spr spectroscopy and surface plasmon fieldenhanced fluorescence spectroscopy spfs are governed by the strong surface plasmon resonancegenerated evanescent field at the metaldielectric interface. Simple evanescent field sensor for nir spectroscopy core. A threedimensional model is formulated within the framework of geometric optics. Analysis of diffusion in polymers using evanescent field.
B evanescent wave at the interface between two media, under total internal reflection. As has been suggested in the literature pertaining to silica bers, bending converts. Here, we achieve the evanescent field absorption spectroscopy on our recently reported. In second part, a refractometric sensor using evanescent field based fiber loop ring down spectroscopy flrds has been implemented in which the output is represented in the form of a time constant. A cylindrical silver halide agx fiber with an ethylenepropylene copolymer epco coated flattened segment was used as an active optical. Dec 24, 2001 this applies, for example, to morphological resonances of dielectric particles with size parameters 1. The model includes various launching conditions, input and output endface fresnel transmission losses, multiple fresnel reflections, bulk absorption, and evanescentwave. This interaction and its resulting family of techniques allow the technique to probe optical properties within a few hundred nanometers of the sample surface. Evaluation of an evanescent fiber optic chemical sensor. Analysis of diffusion in polymers using evanescent field spectroscopy analysis of diffusion in polymers using evanescent field spectroscopy fieldson, gregory t barbari, timothy a. However, molar absorptivities in this spectral region are usually weak, so that highsensitivity measurement devices are required. While conventional surface plasmon resonance spectroscopy allows the observation of surface reactions by means of refractive index changes, spfs additionally. In snom, the excitation laser light is focused through an aperture with a diameter smaller than the excitation wavelength, resulting in an evanescent. Pdf evanescentfield spectroscopy using structured optical.
Evanescent wave fiber optic biosensors are a subset of fiber optic biosensors that perform the sensing function along the fibers cylindrical length. Simple evanescent field sensor for nir spectroscopy. Fiberoptic evanescentwave spectroscopy fews is a novel method for measuring the absorption spectra of samples in contact. Spectroscopy in the middle in frared mir in the spectral range 330 m is. Detection of chargetransfer at the porphyrinsilica interface.
Optical response of magnetic fluorescent microspheres used for force spectroscopy in the evanescent field. In all optical fibers, light propagates by means of total internal reflection, wherein the propagating light is launched into waveguide at angles such that upon reaching the claddingcore interface, the energy is reflected and remains in the core. Fiber optic evanescent field spectroscopy for in situ monitoring of ph levels is presented. Localized and propagating surface plasmon coenhanced. In order to produce modes close to cutoff in the sensing region, tunneling modes were launched into the clad fiber. Evanescent wave coupling is used to excite, for example, dielectric microsphere resonators. An investigation of evanescent wave gas sensing using. A simple fiber optic chemical sensor is reported which may be used to detect in situ and in real time concentrations of gases and liquids. Optical waveguides provide for highly sensitive attenuated total reflection atr spectroscopy in a robust massproducible format, and allow for ultrasmall sample volume, due to the 100 nm scale extent of the evanescent field, and the potential for labonchip integration. Nearinfrared nir spectroscopy is a powerful tool for chemical analysis in applications ranging from biomedicine to analysis of food products and textiles 1.
Temperature sensor using single mode fiber evanescent field absorption. Surface plasmon resonance spectroscopy as a tool for investigating the biochemical and biophysical properties of membrane protein systems. Waveguide evanescent field absorption has been measured as a function of cladding refractive index and bulk absorption coefficient. Atomic and molecular spectroscopy in the evanescent. It allows the measurement of the absorption characteristics of a lossy medium. Thermal nearfields, vibrational spectroscopy, nearfield imaging, chemical spectroscopy, evanescent fields f or over a century the laws of kirchhoff1 and planck2 have fully described farfield thermal emission, the fundamental origin of which lies in. Optical evanescent wave methods for the study of biomolecular. Evanescent field absorption sensing using sapphire fibers. A evanescent wave in a waveguide, in contact with a sample. Thermal nearfields, vibrational spectroscopy, near field imaging, chemical spectroscopy, evanescent fields f or over a century the laws of kirchhoff1 and planck2 have fully described far field thermal emission, the fundamental origin of which lies in the microscopic spacetime fluctuation of charge carriers. The greatest evanescent field amplitude at the interface and the maximum attenuation of the reflectance are observed when a. Optical waveguides provide for highly sensitive attenuated total reflection atr spectroscopy in a. Incident angledependent sers spectra were measured in the evanescent field. Tm according to both effects, the sig nal of an evanescent wave sensor at an absorbing wave length is given by logiio a.
Evanescent wave absorption in an aqueous dye solution has been performed using multimode fused silica fiber which was unclad at the sensing region. Enhanced evanescent field spectroscopy at waveguide surfaces. Weis rm, balakrishnan k, smith b, mcconnell hm 1982 stimulation of fluorescence in a small contact region between rat basophil leukemia cells and planar lipid membrane targets by coherent evanescent radiation. Evanescent field fluorescence microscopy springerlink. Next, we give a brief overview of the fundamental operating principles of ews.
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