Role of waveguide resonance in coupled plasmonic structures using bimetallic nanofilms
26 Oct 2012-Optical Engineering (International Society for Optics and Photonics)-Vol. 51, Iss: 10, pp 103801-103801
TL;DR: In this paper, the authors theoretically analyze waveguide coupled surface plasmon resonance structure to investigate the coupling phenomenon between waveguide resonance and PLASM resonance and found that different modes that are generated are found to have dual contributions of waveguide and PLAsmonic effects, and the important role played by the thickness of the waveguide layer is also established with supporting simulations.
Abstract: We theoretically analyze waveguide coupled surface plasmon resonance structure to investigate the coupling phenomenon between waveguide resonance and plasmonic resonance. Variations of types of metals as well as changes of thickness of the waveguide layer produce some interesting phenomena in the context of coupled plasmonics. Different modes that are generated are found to have dual contributions of waveguide and plasmonic effects. Field enhancement and reflectance contour plots with simultaneous angular and wavelength interrogation give some insight into the effect of waveguide resonance on the performance of nanoplasmonic structure. Figure of merit calculations and comparison of angular and wavelength differential curves of different nanoplasmonic structures can be used to determine the right candidature as regarding the better sensing performance compared to conventional SPR based sensor. Moreover, the important role played by the thickness of the waveguide layer is also established with supporting simulations.
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TL;DR: In this paper, the authors present simulations and experimental SPR data for variety of sensors fabricated by using bimetal (Ag/Au) and multilayer waveguide-coupled Ag/Si3N4+Au structures.
Abstract: Through computer simulations and surface plasmon resonance (SPR) measurements, we establish optimum parameters for the design and fabrication of SPR sensors of high sensitivity, resolution, stability, and long decay-length evanescent fields. We present simulations and experimental SPR data for variety of sensors fabricated by using bimetal (Ag/Au) and multilayer waveguide-coupled Ag/Si3N4/Au structures. The simulations were carried out by using the transfer matrix method in MATLAB environment. Results are presented as functions of the thickness of the metal (Ag or Au) and the waveguide dielectric used in Ag/Si3N4/Au structures. Excellent agreement is observed between the simulations and experiments. For optimized thickness of the Si3N4 waveguide (150 nm), the sensor exhibits very high sensitivity to changes in the refractive index of analytes, Sn≈52°/RIU, extremely high resolution (FWHM≤0.28°), and long penetration depth of evanescent fields (δ≥305nm).
38 citations
TL;DR: In this article, the authors used the Finite Difference Time Domain (FDTD) method to calculate the light absorption enhancement factor of nano-grating assisted metal-semiconductor-metal photodetectors near the design wavelength.
Abstract: Metal–semiconductor–metal photodetectors (MSM-PDs) are utilized for suitable nano-structured fabrications that can play an important role for the development of future high-speed devices to achieve very high responsivity–bandwidth characteristics. Finite-difference time-domain (FDTD) method is used to calculate the light absorption enhancement factor of nano-grating assisted MSM-PDs near the design wavelength by changing the detector's geometrical parameters in comparison with a conventional device (i.e., without the nano-gratings). The substrates containing the aperture and the nano-gratings are optimized in thickness to trigger an extraordinary optical transmission. Besides, this paper demonstrates how the coupling condition satisfies the oscillating charge densities evolution to the surface plasmon polaritons under illumination of a polarized light and the existence of a band gap in the dispersion curve of surface plasmons propagating on periodically corrugated surfaces. The simulated results confirm that the light absorption enhancement factor of nano-grating assisted MSM-PDs is ∼12-times better than the conventional type of MSM-PDs.
23 citations
TL;DR: In this article, the authors proposed a method for determining the correct device parameters, such as reflectivity, phase, field enhancement, and the complex amplitude reflectance Argand diagram (CARAD), in order to optimize the film thickness of mono-and bimetallic plasmonic structures.
Abstract: Metallic film thickness optimization in mono- and bimetallic plasmonic structures has been carried out in order to determine the correct device parameters. Different resonance parameters, such as reflectivity, phase, field enhancement, and the complex amplitude reflectance Argand diagram (CARAD), have been investigated for the proposed optimization procedure. Comparison of mono- and bimetallic plasmonic structures has been carried out in the context of these resonance parameters with simultaneous angular and spectral interrogation. Differential phase analysis has also been performed and its application to sensing has been discussed along with a proposed interferometric set-up.
16 citations
TL;DR: In this paper, the phase dependent resonant behavior along with its complex plane analysis is investigated in the wavelength regime, and the theoretical analysis of differential phase sensitivity in wavelength regime predicts the possibility of detection of refractive index change of the order of 10 −8 RIU.
Abstract: Numerical investigations of metal–dielectric–metal waveguide-coupled dual nanoresonator is demonstrated. Phase dependent resonant behavior along with its complex plane analysis is investigated in wavelength regime. Detailed analysis of the influence of the structural parameters on the resonance curve helps to determine the correct device parameters for different plasmonic applications. This waveguide-coupled plasmonic resonator can be utilized for chemical and biological sensing. In this context, figure of merit related to the asymmetric Fano line shape is redefined, incorporating both differential phase and quality (Q)-factor. Theoretical analysis of differential phase sensitivity in wavelength regime predicts the possibility of detection of refractive index change of the order of 10 −8 RIU.
14 citations
Cites methods from "Role of waveguide resonance in coup..."
...MDM structures are efficiently used as all optical integrated devices and highly sensitive sensors due to the large field enhancement of the waveguide coupled plasmonic mode [28]....
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TL;DR: In this article, the performance of several bimetallic multi-layer metallo-dielectric plasmonic structures has been analyzed three-dimensionalally, along with their reflectance contour plots.
13 citations
References
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TL;DR: In this paper, it has been shown that the non-radiative mode excited by light can also radiate under certain conditions if they are excited by electrons (grazing incidence of electrons on a rough surface or at normal incidence on a grating).
Abstract: There are two modes of surface plasma waves: 1) Non-radiative modes with phase velocities Cü/k smaller than the velocity of light c. They cannot decay into photons in general. 2) Radiative modes with (o/k > c which couple directly with photons 1. The following paper is concerned with the excitation of these modes by light and their decay into photons. It has been shown that the radiative mode on thin silverand potassium-films can be excited by light and that the mode reradiates light almost into all directions with an intensity maximum at the plasma frequency cOp 2. It had been further observed that the non-radiative modes radiate under certain conditions if they are excited by electrons (grazing incidence of electrons on . a rough surface3 or at normal incidence on a grating 4) . The mechanism of this emission is in these cases always the same: The \"wave vector\" of the roughness of the surface or its irregularity changes the plasmon wave vector k so that a) in the case of the radiative mode light emission is found in directions in addition to that of reflexion and transmission, b) in the case of the non-radiative mode its wave vector is reduced so that the condition /c0, the wave vector of the inhomogeneous wave is (co/c) • Vsq' sin 0O (fq = 2.16 for quartz) and thus can excite a non radiative mode on the boundary of the prism for j/fq sin 0O > 1 or 90° > @o > 43°. If one vaporises a silver film directly on the quartz surface the inhomogeneous light wave penetrates into the silver film and excites a nonradiative mode on the boundary silver/air. The excitation will be highest for those frequencies which fulfill the dispersion relation of these surface plasmons.
2,790 citations
TL;DR: In this article, the dispersion relations for surface plasma oscillations in normal metals are investigated for single-and multiple-film systems taking retardation effects into account, and two types of possible modes of oscillation are found.
Abstract: The dispersion relations for surface plasma oscillations in normal metals are investigated for single- and multiple-film systems taking retardation effects into account. The simple dielectric function $\ensuremath{\epsilon}(\ensuremath{\omega})=1\ensuremath{-}\frac{{{\ensuremath{\omega}}_{p}}^{2}}{{\ensuremath{\omega}}^{2}}$ is found to be adequate for the high-frequency region in which oscillations remain undamped. Two types of possible modes of oscillation are found. One type corresponds to dispersion relations which behave linearly for not-so-high frequency, with a phase velocity always smaller than the velocity of light in the dielectric, but at least ten times larger than the Fermi velocity, while the other type consists of high-frequency modes ($\ensuremath{\omega}\ensuremath{\sim}{\ensuremath{\omega}}_{p}$). The role of these oscillations in the problem of transition radiation is reexamined. In the case of a thin metal film, a new interpretation is proposed for the peak observed in the transition radiation spectrum. Finally, the work is extended to superconducting metals where, in the frequency range $\ensuremath{\hbar}\ensuremath{\omega}l2\ensuremath{\Delta}$ ($2\ensuremath{\Delta}$ is the superconducting energy gap), we have justified the use of a dielectric function of the same functional form as given above but with ${{\ensuremath{\omega}}_{p}}^{2}$ replaced by an almost frequency-independent quantity ${{\ensuremath{\omega}}_{\mathrm{ps}}}^{2}$, where ${\ensuremath{\omega}}_{\mathrm{ps}}=\frac{c}{{\ensuremath{\lambda}}_{\mathrm{ps}}}$ and ${\ensuremath{\lambda}}_{\mathrm{ps}}$ is the actual penetration depth. In this frequency range, the oscillations are essentially undamped and play an important role in the electromagnetic properties of the multiple-film systems, and particularly when the systems exhibit the ac Josephson effect.
1,258 citations
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1,085 citations
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...r lk 1⁄4 nk cos θl − nl cos θk nk cos θl þ nl cos θk ; (6)...
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TL;DR: The dispersion equation of injected surface-plasma waves that propagate on thin metal films has been solved as a function of the film thickness, and splitting of the modes into two branches is observed.
Abstract: The dispersion equation of injected surface-plasma waves that propagate on thin metal films has been solved as a function of the film thickness, and splitting of the modes into two branches is observed. For one branch the imaginary part of the propagation constant goes to zero as the thickness of the metal decreases. Reflectivity calculations agree with this result, which predicts that one can obtain propagation distances that are more than 1 order of magnitude larger than observed before.
881 citations
"Role of waveguide resonance in coup..." refers background in this paper
...51(10) Bera and Ray: Role of waveguide resonance in coupled plasmonic structures : : :...
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...jHyð3∕2Þj(2) jHyð1∕2Þj(2) 1⁄4 jtTM 123j(2) 1⁄4 t 12 t 23 expðikz2d2Þ 1þ r 12 r 23 expðikz2d2Þ 2; (10)...
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...51(10) Optical Engineering 51(10), 103801 (October 2012)...
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TL;DR: Theoretical analysis and comparison of the sensitivity of surface plasmon resonance (SPR) sensors using diffraction at gratings and attenuated total reflection (ATR) in prism couplers for two detection methods-resonant angle interrogation and resonant wavelength interrogation is presented in this article.
Abstract: Theoretical analysis and comparison of the sensitivity of surface plasmon resonance (SPR) sensors using diffraction at gratings and attenuated total reflection (ATR) in prism couplers for two detection methods-resonant angle interrogation and resonant wavelength interrogation is presented. Analytical expressions for sensitivity of these SPR sensors are derived and the influence of the major design parameters of the sensing structures on the sensor sensitivity is discussed. The analysis shows that grating-based SPR sensors using wavelength interrogation are much less sensitive then their prism coupler-based counterparts. In the angular interrogation mode, the sensitivity of SPR sensors using diffraction gratings depends on the diffraction order and does not differ much from that of SPR sensors based on prism couplers.
632 citations