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Spoof localized surface plasmons on ultrathin textured MIM ring resonator with enhanced resonances.

Zhou YJ, Xiao QX, Yang BJ - Sci Rep (2015)

Bottom Line: Quality factors of resonance peaks have become much larger and multipolar resonances modes can be easily observed on the textured MIM ring resonator excited by a microstrip line.We have shown that the fabricated resonator is sensitive to the variation of both the dielectric constant and the thickness of surrounding materials under test.The spoof plasmonic resonator can be used as key elements to provide many important device functionalities such as optical communications, signal processing, and spectral engineering in the plasmonic integration platform.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Shanghai University, Shanghai 200072, China.

ABSTRACT
We numerically demonstrate that spoof localized surface plasmons (LSPs) resonant modes can be enhanced based on ultrathin corrugated metal-insulator-metal (MIM) ring resonator. Further enhancement of the LSPs modes has been achieved by incorporating an efficient and ease-of-integration exciting method. Quality factors of resonance peaks have become much larger and multipolar resonances modes can be easily observed on the textured MIM ring resonator excited by a microstrip line. Experimental results validate the high-efficiency excitation and resonance enhancements of spoof LSPs modes on the MIM ring resonator in the microwave frequencies. We have shown that the fabricated resonator is sensitive to the variation of both the dielectric constant and the thickness of surrounding materials under test. The spoof plasmonic resonator can be used as key elements to provide many important device functionalities such as optical communications, signal processing, and spectral engineering in the plasmonic integration platform.

No MeSH data available.


Schematic picture of (a) the single straight corrugated metallic strip and (b) the straight corrugated MIM waveguide. (c) The dispersion relations of spoof SPPs on the single or MIM corrugated strips. (d) The energy flow (group) velocity vg of the spoof SPPs on the single or MIM corrugated strips.
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f2: Schematic picture of (a) the single straight corrugated metallic strip and (b) the straight corrugated MIM waveguide. (c) The dispersion relations of spoof SPPs on the single or MIM corrugated strips. (d) The energy flow (group) velocity vg of the spoof SPPs on the single or MIM corrugated strips.

Mentions: To reveal the nature of spoof LSPs in the proposed spoof plasmonic resonator, we firstly investigate the EM characteristics of spoof SPPs on the straight spoof plasmonic structures, since the asymptotic frequency of a straight plasmonic structure can be maintained in the spoof plasmonic resonator. The textured disk arises from the single straight corrugated metallic strip shown in Fig. 2(a), while the proposed corrugated MIM ring resonator derives from straight corrugated MIM waveguide illustrated in Fig. 2(b). For simplicity, the insulator between the two metal strips is set as air. Here the parameters are a = 0.4p, p = 0.94 mm, h = 3 mm, g = 1 mm, and s = 2 mm. The dispersion relations of spoof SPPs on the single or MIM corrugated strips are calculated by use of the eigenmode solver of the commercial software, CST Microwave Studio. The dispersion curves are plotted in Fig. 2(c). Only one unit cell (see the inset) is used in the simulation. The energy flow (group) velocity vg of the spoof SPPs can be calculated from the dispersion curves according to vg = dω/dβ and the results are shown in Fig. 2(d). From these curves, we can obtain several conclusions. First, it can be seen that the asymptotic frequency of the corrugated MIM waveguide is lower than that of the single corrugated metallic strip. For the same operating frequency, the plasmonic wave vector β of spoof SPPs in the corrugated MIM strips becomes larger. Hence, stronger field confinement can be achieved in the corrugated MIM waveguide, since the SPP fields in the air fall off as with , where kz is the space wave vector in z-direction (perpendicular to the metal surface), ω is the angular frequency, ε0 and c are the permittivity and light velocity in the air. Second, close to the asymptotic frequency, the dispersion curve for the corrugated MIM strips slowly becomes flat in a large wave-number range, rather than abruptly turning flat as in the case of single corrugated metallic strip. In other words, the group velocity vg of the spoof SPPs in the corrugated MIM waveguide decreases more slowly than that in the single corrugated strip. The energy incident from the input port will be totally reflected before its group velocity decreases to zero, due to the strong intermodal coupling between the forward and backward modes49. Hence, if we define that vgmin is the minimum group velocity where the energy flow velocity of the spoof SPPs has practically reached, there exists a cutoff wave-vector βmax where the dispersion curve has practically reached its asymptotic frequency33 and the βmax of the corrugated MIM strips will be larger than that of single corrugated metallic strip. Since only resonance modes with wave vectors smaller than βmax can form resonances, the number of resonance modes supported by the corrugated MIM ring resonator should be larger than that supported by the corrugated disk.


Spoof localized surface plasmons on ultrathin textured MIM ring resonator with enhanced resonances.

Zhou YJ, Xiao QX, Yang BJ - Sci Rep (2015)

Schematic picture of (a) the single straight corrugated metallic strip and (b) the straight corrugated MIM waveguide. (c) The dispersion relations of spoof SPPs on the single or MIM corrugated strips. (d) The energy flow (group) velocity vg of the spoof SPPs on the single or MIM corrugated strips.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4588594&req=5

f2: Schematic picture of (a) the single straight corrugated metallic strip and (b) the straight corrugated MIM waveguide. (c) The dispersion relations of spoof SPPs on the single or MIM corrugated strips. (d) The energy flow (group) velocity vg of the spoof SPPs on the single or MIM corrugated strips.
Mentions: To reveal the nature of spoof LSPs in the proposed spoof plasmonic resonator, we firstly investigate the EM characteristics of spoof SPPs on the straight spoof plasmonic structures, since the asymptotic frequency of a straight plasmonic structure can be maintained in the spoof plasmonic resonator. The textured disk arises from the single straight corrugated metallic strip shown in Fig. 2(a), while the proposed corrugated MIM ring resonator derives from straight corrugated MIM waveguide illustrated in Fig. 2(b). For simplicity, the insulator between the two metal strips is set as air. Here the parameters are a = 0.4p, p = 0.94 mm, h = 3 mm, g = 1 mm, and s = 2 mm. The dispersion relations of spoof SPPs on the single or MIM corrugated strips are calculated by use of the eigenmode solver of the commercial software, CST Microwave Studio. The dispersion curves are plotted in Fig. 2(c). Only one unit cell (see the inset) is used in the simulation. The energy flow (group) velocity vg of the spoof SPPs can be calculated from the dispersion curves according to vg = dω/dβ and the results are shown in Fig. 2(d). From these curves, we can obtain several conclusions. First, it can be seen that the asymptotic frequency of the corrugated MIM waveguide is lower than that of the single corrugated metallic strip. For the same operating frequency, the plasmonic wave vector β of spoof SPPs in the corrugated MIM strips becomes larger. Hence, stronger field confinement can be achieved in the corrugated MIM waveguide, since the SPP fields in the air fall off as with , where kz is the space wave vector in z-direction (perpendicular to the metal surface), ω is the angular frequency, ε0 and c are the permittivity and light velocity in the air. Second, close to the asymptotic frequency, the dispersion curve for the corrugated MIM strips slowly becomes flat in a large wave-number range, rather than abruptly turning flat as in the case of single corrugated metallic strip. In other words, the group velocity vg of the spoof SPPs in the corrugated MIM waveguide decreases more slowly than that in the single corrugated strip. The energy incident from the input port will be totally reflected before its group velocity decreases to zero, due to the strong intermodal coupling between the forward and backward modes49. Hence, if we define that vgmin is the minimum group velocity where the energy flow velocity of the spoof SPPs has practically reached, there exists a cutoff wave-vector βmax where the dispersion curve has practically reached its asymptotic frequency33 and the βmax of the corrugated MIM strips will be larger than that of single corrugated metallic strip. Since only resonance modes with wave vectors smaller than βmax can form resonances, the number of resonance modes supported by the corrugated MIM ring resonator should be larger than that supported by the corrugated disk.

Bottom Line: Quality factors of resonance peaks have become much larger and multipolar resonances modes can be easily observed on the textured MIM ring resonator excited by a microstrip line.We have shown that the fabricated resonator is sensitive to the variation of both the dielectric constant and the thickness of surrounding materials under test.The spoof plasmonic resonator can be used as key elements to provide many important device functionalities such as optical communications, signal processing, and spectral engineering in the plasmonic integration platform.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Shanghai University, Shanghai 200072, China.

ABSTRACT
We numerically demonstrate that spoof localized surface plasmons (LSPs) resonant modes can be enhanced based on ultrathin corrugated metal-insulator-metal (MIM) ring resonator. Further enhancement of the LSPs modes has been achieved by incorporating an efficient and ease-of-integration exciting method. Quality factors of resonance peaks have become much larger and multipolar resonances modes can be easily observed on the textured MIM ring resonator excited by a microstrip line. Experimental results validate the high-efficiency excitation and resonance enhancements of spoof LSPs modes on the MIM ring resonator in the microwave frequencies. We have shown that the fabricated resonator is sensitive to the variation of both the dielectric constant and the thickness of surrounding materials under test. The spoof plasmonic resonator can be used as key elements to provide many important device functionalities such as optical communications, signal processing, and spectral engineering in the plasmonic integration platform.

No MeSH data available.