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Andam N, Refki S, Hayashi S, Sekkat Z. Plasmonic mode coupling and thin film sensing in metal-insulator-metal structures. Sci Rep 2021; 11:15093. [PMID: 34301973 PMCID: PMC8302593 DOI: 10.1038/s41598-021-94143-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 07/05/2021] [Indexed: 11/09/2022] Open
Abstract
Optical sensors based on surface plasmon resonance (SPR) in the attenuated total reflection (ATR) configuration in layered media have attracted considerable attention over the past decades owing to their ability of label free sensing in biomolecular interaction analysis, and highly sensitive detection of changes in refractive index and thickness, i.e. the optical thickness, of thin film adsorbates (thin film sensing). Furthermore, SPR is highly sensitive to the refractive index of the medium adjacent to the bare metal, and it allows for bulk sensing as well. When deposited at the metal/air interface, an adsorbed layer disturbs the highly localized, i.e. bound, wave at this interface and changes the plasmon resonance to allow for sensing in angular or wavelength interrogation and intensity measurement modes. A high degree of sensitivity is required for precise and efficient sensing, especially for biomolecular interaction analysis for early stage diagnostics; and besides conventional SPR (CSPR), several other configurations have been developed in recent years targeting sensitivity, including long-range SPR (LRSPR) and waveguide-coupled SPR (WGSPR) observed in MIM structures, referred here to by MIM modes, resulting from the coupling of SPRs at I/M interfaces, and Fano-type resonances occurring from broad and sharp modes coupling in layered structures. In our previous research, we demonstrated that MIM is better than CSPR for bulk sensing, and in this paper, we show that CSPR is better than MIM for thin film sensing for thicknesses of the sensing layer (SL) larger than 10 nm. We discuss and compare the sensitivity of CSPR and MIM for thin film sensing by using both experiments and theoretical calculations based on rigorous electromagnetic (EM) theory. We discuss in detail MIM modes coupling and anti-crossing, and we show that when a thin film adsorbate, i.e. a SL), is deposited on top of the outermost-layer of an optimized MIM structure, it modifies the characteristics of the coupled modes of the structure, and it reduces the electric field, both inside the SL and at the SL/air interface, and as a result, it decreases the sensitivity of the MIM versus the CSPR sensor. Our work is of critical importance to plasmonic mode coupling using MIM configurations, as well as to optical bio- and chemical-sensing.
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Affiliation(s)
- N Andam
- Department of Chemistry, Faculty of Sciences, University Mohammed V, Rabat, Morocco.,Optics and Photonics Center, Moroccan Foundation for Advanced Science and Innovation and Research, University Mohammed VI Polytechnic, Rabat, Morocco
| | - S Refki
- Optics and Photonics Center, Moroccan Foundation for Advanced Science and Innovation and Research, University Mohammed VI Polytechnic, Rabat, Morocco
| | - S Hayashi
- Optics and Photonics Center, Moroccan Foundation for Advanced Science and Innovation and Research, University Mohammed VI Polytechnic, Rabat, Morocco.,Graduate School of Engineering, Kobe University, Kobe, 657-8501, Japan
| | - Z Sekkat
- Department of Chemistry, Faculty of Sciences, University Mohammed V, Rabat, Morocco. .,Optics and Photonics Center, Moroccan Foundation for Advanced Science and Innovation and Research, University Mohammed VI Polytechnic, Rabat, Morocco. .,Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.
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Meng QQ, Zhao X, Lin CY, Chen SJ, Ding YC, Chen ZY. Figure of Merit Enhancement of a Surface Plasmon Resonance Sensor Using a Low-Refractive-Index Porous Silica Film. SENSORS 2017; 17:s17081846. [PMID: 28796155 PMCID: PMC5580096 DOI: 10.3390/s17081846] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 08/03/2017] [Accepted: 08/08/2017] [Indexed: 11/22/2022]
Abstract
In this paper; the surface plasmon resonance (SPR) sensor with a porous silica film was studied. The effect of the thickness and porosity of the porous silica film on the performance of the sensor was analyzed. The results indicated that the figure of merit (FOM) of an SPR sensor can be enhanced by using a porous silica film with a low-refractive-index. Particularly; the FOM of an SPR sensor with 40 nm thick 90% porosity porous silica film; whose refractive index is 1.04 was improved by 311% when compared with that of a traditional SPR sensor. Furthermore; it was found that the decrease in the refractive index or the increase in the thickness of the low-refractive-index porous silica film can enlarge the FOM enhancement. It is believed that the proposed SPR sensor with a low-refractive-index porous silica film will be helpful for high-performance SPR sensors development.
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Affiliation(s)
- Qing-Qing Meng
- College of Science, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Xin Zhao
- College of Science, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Cheng-You Lin
- College of Science, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Shu-Jing Chen
- School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083, China.
| | - Ying-Chun Ding
- College of Science, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Zhao-Yang Chen
- College of Science, Beijing University of Chemical Technology, Beijing 100029, China.
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Sekkat Z, Hayashi S, Nesterenko DV, Rahmouni A, Refki S, Ishitobi H, Inouye Y, Kawata S. Plasmonic coupled modes in metal-dielectric multilayer structures: Fano resonance and giant field enhancement. OPTICS EXPRESS 2016; 24:20080-20088. [PMID: 27607617 DOI: 10.1364/oe.24.020080] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We provide an overview of Fano resonance and plasmon induced transparency (PIT) as well as on plasmons coupling in planar structures, and we discuss their application in sensing and enhanced spectroscopy. Metal-insulator-metal (MIM) structures, which are known to support symmetric and anti-symmetric surface plasmon polaritons (SPPs) arising from the coupling between two SPPs at the metal-insulator interfaces, exhibit anticrossing behavior of the dispersion relations arising from the coupling of the symmetric SPP and the metal/air SPP. Multilayer structures, formed by a metal film and a high-index dielectric waveguide (WG), separated by a low-index dielectric spacer layer, give narrow resonances of PIT and Fano line shapes. An optimized Fano structure shows a giant field intensity enhancement value of 106 in air at the surface of the high-index dielectric WG. The calculated field enhancement factor and the figure of merit for the sensitivity of the Fano structure in air can be 104 times as large as those of the conventional surface plasmon resonance and WG sensors.
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Chen Z, Zhao X, Lin C, Chen S, Yin L, Ding Y. Figure of merit enhancement of surface plasmon resonance sensors using absentee layer. APPLIED OPTICS 2016; 55:6832-6835. [PMID: 27607256 DOI: 10.1364/ao.55.006832] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
By adding an absentee layer on the top of the metallic layer, the figure of merit (FOM) of a surface plasmon resonance (SPR) sensor with Kretschmann configuration was enhanced, without changing the resonance angle and the reflectance at the resonance angle. Comparing with a traditional SPR sensor, the FOM of the SPR sensor with an absentee layer composed of either 1367 nm thick KCl or 235 nm thick Si3N4 can be improved by 5.53% or 11.41%, respectively. The enhancement of the FOM should be attributed to the faster decrease of the full width at half-maximum than the sensitivity after an absentee layer was applied in the SPR sensor.
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Ee HS, Park HG, Kim SK. Design of high Q-factor metallic nanocavities using plasmonic bandgaps. APPLIED OPTICS 2016; 55:1029-1033. [PMID: 26906371 DOI: 10.1364/ao.55.001029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The surface plasmon polariton modes often excited in metallic nanocavities enable the miniaturization of photonic devices, even beyond the diffraction limit, yet their severe optical losses deteriorate device performance. This study proposes a design of metallic nanorod cavities coupled to plasmonic crystals with the aim of reducing the radiation loss of surface plasmon modes. Periodic Ag disks placed on an insulator-metal substrate open a substantial amount of plasmonic bandgaps (e.g., Δλ=290 nm at λ=1550 nm) by modifying their diameter and thickness. When an Ag nanorod with a length of ∼400 nm is surrounded by the periodic Ag disks, its Q-factor increases up to 127, yielding a 16-fold enhancement compared with a bare Ag nanorod, while its mode volume can be as small as 0.03(λ/2n)³. Ag nanorods with gradually increasing lengths exhibit high Q-factor plasmonic modes that are tunable within the plasmonic bandgap. These numerical studies on low-radiation-loss plasmonic modes excited in metallic nanocavities will promote the development of ultrasmall plasmonic devices.
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