Experiments of microwave spectroscopy with cavity spectrometers utilizing the evanescent field extending outside dielectric resonatos. In the last decade fiberoptic, evanescentwave spec troscopy 1fews2 has become a popular analytical method for ir absorbance spectroscopy. A portable sensor system for the simultaneous detection of multiple environmentally relevant volatile organic compounds vocs in real seawater based on fourier transform infrared fiberoptic evanescent wave spectroscopy ftirfews was developed. Analysis of diffusion in polymers using evanescent field spectroscopy analysis of diffusion in polymers using evanescent field spectroscopy fieldson, gregory t barbari, timothy a. Nearinfrared nir spectroscopy is a powerful tool for chemical analysis in applications ranging from biomedicine to analysis of food products and textiles 1. 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. Mar 01, 2015 side polished fiber as an evanescent field based sensor element has been fabricated with a low insertion loss of 0. 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. Evanescent wave fiber optic biosensors are a subset of fiber optic biosensors that perform the sensing function along the fibers cylindrical length.
We performed an optogalvanic spectroscopy experiment with the evanescent light to observe resonances from atoms located very close to the surface. Fiberoptic evanescentwave spectroscopy fews is a novel method for measuring the absorption spectra of samples in contact. Incident angledependent sers spectra were measured in the evanescent field. Analysis of diffusion in polymers using evanescent field spectroscopy gregory t. In snom, the excitation laser light is focused through an aperture with a diameter smaller than. However, molar absorptivities in this spectral region are usually weak, so that highsensitivity measurement devices are required. A cylindrical silver halide agx fiber with an ethylenepropylene copolymer epco coated flattened segment was used as an active optical. Therefore, many groups conducted biomedical researches based on atr spectroscopy. B evanescent wave at the interface between two media, under total internal reflection. While conventional surface plasmon resonance spectroscopy allows the observation of surface reactions by means of refractive index changes, spfs additionally. 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. Chemical sensor for monitoring aqueous volatile organic compounds dianna s. Pdf this paper discusses the theoretical and experimental implications of tapering a multimode optical fiber with a view to its use in. Surface plasmon resonance spectroscopy as a tool for investigating the biochemical and biophysical properties of membrane protein systems.
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. Ir absorption spectra of methanol, ethanol, isopropa nol, acetone, ethanoic acid, water, hexane, and. 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. We propose a bimetallic waveguidecoupled surface plasmon resonance wcspr configuration to enhance raman scattering with an evanescent field excited using surface plasmons. A threedimensional model is formulated within the framework of geometric optics. Evanescent field spectroscopy using structured optical fibers. It allows the measurement of the absorption characteristics of a lossy medium. 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. Optical response of magnetic fluorescent microspheres used for force spectroscopy in the evanescent field. The localized and propagating surface plasmon coenhanced raman scattering of 4mercaptopyridine was observed based on evanescent field excitation.
Evaluation of an evanescent fiber optic chemical sensor for. Evanescent absorbance values for methylene blue in a concentration range 3. In snom, the excitation laser light is focused through an aperture with a diameter smaller than the excitation wavelength, resulting in an evanescent. In 20, shiraga et al presented a method to determine the complex dielectric constant of a cell. 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. Localized and propagating surface plasmon coenhanced. Enhanced evanescent field spectroscopy at waveguide surfaces. Nearfield spectroscopy of single molecules at room temperature. Temperature sensor using single mode fiber evanescent field absorption. 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. Infrared spectroscopy is performed in this format when the sample to be examined is. Evanescent field in surface plasmon resonance and surface. Cladding of plastic clad silica fiber is replaced with polymethyl methacrylate doped with ph sensitive.
Electrochemical optical waveguide lightmode spectroscopy. 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. In order to produce modes close to cutoff in the sensing region, tunneling modes were launched into the clad fiber. Optical evanescent wave methods for the study of biomolecular interactions volume 29 issue 1 peter b. Incident angledependent sers spectra were measured in the. 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. Simple evanescent field sensor for nir spectroscopy. Integrated plasmonenhanced raman scattering i pers. Pdf optical response of magnetic fluorescent microspheres. Evanescent wave coupling is used to excite, for example, dielectric microsphere resonators. 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. View the article pdf and any associated supplements and figures for a period of 48 hours. The wcspr configuration is a fivephase kretschmann resonance setup composed of a k9 prisminner ag filmmgf2 filmouter ag filmwater structure.
Optical evanescent wave methods for the study of biomolecular. Integrated plasmonenhanced raman scattering ipers spectroscopy. Evanescent wave spectroscopy of number of charges because of the difference between the ionisation crosssections. Evanescent wave coupling is commonly used in photonic and nanophotonic devices as waveguide sensors or couplers see e. Parriaux singlemode fiber evanescent wave spectroscopy, proc. Evanescent waves from newtonian optics to atomic optics. We detect trace gases at ppb levels using evanescentfield absorption spectroscopy in microring resonators coated with sorbent polymers. Crossley,2 1interdisciplinary photonics laboratories ipl, school of chemistry, 222 madsen building f09, university of.
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. Electrochemical optical waveguide lightmode spectroscopy ec. 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. In situ monitoring of ph level with fiber optic evanescent. 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. Localized and propagating surface plasmon coenhanced raman.
Spectroscopy in the middle in frared mir in the spectral range 330 m is. Theory of fiberoptic, evanescentwave spectroscopy and. Refractometry using evanescent field based fiber loop. We detect trace gases at ppb levels using evanescent field absorption spectroscopy in microring resonators coated with sorbent polymers. Next, we give a brief overview of the fundamental operating principles of ews. The greatest evanescent field amplitude at the interface and the maximum attenuation of the reflectance are observed when a. The overtone spectra derive from midinfrared resonances that provide a signature of analyte toxicity. Theory of fiberoptic, evanescentwave spectroscopy and sensors. 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. Optical waveguides provide for highly sensitive attenuated total reflection atr spectroscopy in a. Simple evanescent field sensor for nir spectroscopy core. The greatest evanescent field amplitude at the interface and the maximum attenuation of the reflectance are observed when a nonabsorbing. Osa waveguide evanescent field spectroscopy of trace gases.
A new technique for ir spectroscopic measure merits of liquids, pastes and thin films is reported. Infrared spectroscopy is performed in this format when the sample to be examined is highly absorbing. Detection of chargetransfer at the porphyrinsilica interface. These layers draw out the optical field in the vicinity of probing and take advantage of field localisation. 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. Penetrationdepth characteristics of evanescent fields at. Results are reported, indicating the advantages ad the possible applications of the new technique. Simple evanescent field sensor for nir spectroscopy eprints. Pdf evanescentfield spectroscopy using structured optical. A simple theory for interpreting these results has been developed. However, since there is no discontinuity in the field, the field actually decays from its full strength right at the interface to near zero, in a. This interaction and its resulting family of techniques allow the technique to probe optical properties within a few hundred nanometers of the sample surface. Fiber optic evanescent field spectroscopy for in situ monitoring of ph levels is presented. 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.
Chen 1 institute of microelectronics, astar agency for science, technology and research, singapore and 2 microelecronics center, school of eee, nanyang technological university. Simple evanescent field sensor for nir spectroscopy alina karabchevsky, ping hua and james s. Waveguide evanescent field absorption has been measured as a function of cladding refractive index and bulk absorption coefficient. Wilkin son optoelectronics research centre, univers ity of southampton, southampton, uk. Evanescentwave infrared spectroscopy with flattened fibers. Evanescent wave article about evanescent wave by the. 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. A new strategy named integrated plasmonenhanced raman scattering ipers spectroscopy that features a configuration of evanescent field excitation and inverted collection is presented, which well. Tm according to both effects, the sig nal of an evanescent wave sensor at an absorbing wave length is given by logiio a.
A general theory for fiberoptic, evanescentwave spectroscopy and sensors is presented for straight, uncladded, stepindex, multimode fibers. Here, we achieve the evanescent field absorption spectroscopy on our recently reported. Evanescent wave article about evanescent wave by the free. 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. Analysis of diffusion in polymers using evanescent field spectroscopy. Pdf evanescent wave absorption spectroscopy by means of bi. 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. We have used evanescentwave coupling to record the. This applies, for example, to morphological resonances of dielectric particles with size parameters 1. Atomic and molecular spectroscopy in the evanescent. Evanescent wave absorption spectroscopy using multimode. 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 wave intensity is indeed mostly localized within 1. Pdf theory of fiberoptic, evanescentwave spectroscopy and. The sensor, comprised of a single led source and a claddingfree multimode fiber, operates on the principle of evanescent field and differential spectroscopy. 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. Evanescentfield spectroscopy using structured optical fibers.
Schematic of experimental setup for excitation and detection of evanescent. 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. Surface plasmon fieldenhanced fluorescence spectroscopy. As has been suggested in the literature pertaining to silica bers, bending converts.
An allfiber singlemode spectroscopic sensor has been realised. Evanescent field spectroscopy with optical fibers for. Sensors free fulltext toward the required detection. Evaluation of an evanescent fiber optic chemical sensor. Evanescent coupling, as near field interaction, is one of the concerns in electromagnetic compatibility. Evanescent field fluorescence microscopy springerlink. The model includes various launching conditions, input and output endface fresnel transmission losses, multiple fresnel reflections, bulk absorption, and evanescentwave. 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. 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. 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. Pdf simple evanescent field sensor for nir spectroscopy.
Pdf a general theory for fiberoptic, evanescentwave spectroscopy and sensors is presented for straight, uncladded, stepindex, multimode fibers. A evanescent wave in a waveguide, in contact with a sample. 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. 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. An investigation of evanescent wave gas sensing using. Evanescent wave absorption in an aqueous dye solution has been performed using multimode fused silica fiber which was unclad at the sensing region. The evanescent wave extends into and interacts with the sample 27, leading to the high sensitivity detection for the few sample.
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