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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.


(a) Schematic picture of the proposed corrugated MIM ring resonator under the excitation of a plane wave. (b) The calculated ECS spectra. (c) Schematic picture of the corrugated MIM ring resonator under the excitation of a monopole source. (d) The probed near-field response spectra. (e–k) The 2D electric-field distributions on the plane 0.5 mm above the MIM ring resonator at the resonant frequencies marked by M1-M7, which are located at 3.87, 7.89, 9.97, 11.4, 12.13, 13.02, and 13.4 GHz.
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f4: (a) Schematic picture of the proposed corrugated MIM ring resonator under the excitation of a plane wave. (b) The calculated ECS spectra. (c) Schematic picture of the corrugated MIM ring resonator under the excitation of a monopole source. (d) The probed near-field response spectra. (e–k) The 2D electric-field distributions on the plane 0.5 mm above the MIM ring resonator at the resonant frequencies marked by M1-M7, which are located at 3.87, 7.89, 9.97, 11.4, 12.13, 13.02, and 13.4 GHz.

Mentions: Figure 4(a) depicts the schematic configuration of the proposed ultrathin corrugated MIM ring resonator, which is composed of two closed corrugated metal strips. The parameters of the inner corrugated metallic disk are the same as those of the disk in Fig. 1(a). The outer radius R1 and the inner radius R2 of the opposite closed corrugated metal are set to be 9 mm and 6 mm, respectively. The groove depth, groove period and groove width of the outer closed corrugated metal grating are denoted by h1, p1, a1, and they are set to be h1 = h = 3 mm, p1 = 2πR1/N = 0.94 mm, and a1 = 0.4p1. Both the width w and the length l of the whole structure are 25 mm. The width g of the air is optimized to 1 mm. The optimization mechanism will be discussed in the later section. Figure 4(b) provides the simulated ECS spectrum of the ultrathin corrugated MIM ring resonator under the excitation of a plane wave, where marked M1-M4 peaks correspond to multiple plasmonic resonances with the dipole, quadrupole, hexapole, and octopole modes at frequencies 3.64, 6.31, 9.55, and 11.71 GHz, respectively. To excite the spoof LSPs by use of a monopole source, the monopole should be parallel to the structure surface, as depicted in Fig. 4(c), to make sure that the magnetic field generated by the monopole source is perpendicular to the structure surface. Hence the magnetic field matches that of spoof LSPs in the corrugated ring structure. The near-field response is plotted in Fig. 4(d), in which seven peaks M1-M7 located at 3.87, 7.89, 9.97, 11.4, 12.13, 13.02, and 13.4 GHz can be observed. Several conclusions can be drawn by comparing Fig. 4 with Fig. 1. First, more resonance modes in the corrugated MIM ring resonator can be observed, no matter a plane wave or a monopole source is used to excite spoof LSPs. The result verifies the theoretical analysis in Fig. 2(c,d). Second, the resonances have been enhanced, which is consistent with the analysis in Fig. 3(c–e). For example, for the case under the excitation of a plane wave, Q factor of M1 resonance peak has been increased a little, changing from 2.7 to 4.2. For the case under the excitation of a monopole source, the dipole resonance is obviously enhanced, although its Q factor is still only 3.17. Q factor of M4 resonance peak has been increased from 40.4 to 54.28. Third, spoof LSPs in the corrugated MIM ring structure are actually standing surface waves31. To form resonances in the circular resonator, the well-known requirement to be satisfied is L = nλg, where L is the circumference of the circular resonator, λg is the guided wavelength on the straight corrugated MIM waveguide, and n is a positive integer. Since groove width of the corrugated MIM ring resonator is non-uniform, we choose a medium groove width to check whether the above relation is satisfied. Hence L = 2πR2 = 37.7 mm and the groove width is a2 = 0.4p2, where p2 = 2πR2/N = 0.63 mm. The wavelength at the resonant modes marked by M1-M7 can be calculated by λg = 2π/β. The calculated results are λgM1 = 39.1 mm, λgM2 = 17.2 mm, λgM3 = 12.2 mm, λgM4 = 9.3 mm, λgM5 = 8.0 mm, λgM6 = 6.6 mm, and λgM7 = 6.0 mm. It can be verified that the circumference L approximately satisfy L ≈ Mi × λgMi, (i = 1, 2, 3……). Lastly, comparing Fig. 4(d) with Fig. 4(b), we can see that the higher modes are also difficult to excite by a plane wave due to the low matching between the field of the plane wave and that of the spoof LSPs for higher resonant modes. In order to verify the multipolar spoof LSPs resonant modes on the corrugated MIM structure excited by the monopole antenna, 2D distributions of electric-field (z-components) on the plane 0.5 mm above the corrugated MIM ring resonator at the resonant frequencies are illustrated in Fig. 4(e–k), where the color scale ranges from red (the highest positive intensity) to blue (the lowest negative intensity). It can be seen that all the resonance modes at M1-M7 can be recognized, while the field patterns in M6 and M7 are not clearly observable.


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

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

(a) Schematic picture of the proposed corrugated MIM ring resonator under the excitation of a plane wave. (b) The calculated ECS spectra. (c) Schematic picture of the corrugated MIM ring resonator under the excitation of a monopole source. (d) The probed near-field response spectra. (e–k) The 2D electric-field distributions on the plane 0.5 mm above the MIM ring resonator at the resonant frequencies marked by M1-M7, which are located at 3.87, 7.89, 9.97, 11.4, 12.13, 13.02, and 13.4 GHz.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4588594&req=5

f4: (a) Schematic picture of the proposed corrugated MIM ring resonator under the excitation of a plane wave. (b) The calculated ECS spectra. (c) Schematic picture of the corrugated MIM ring resonator under the excitation of a monopole source. (d) The probed near-field response spectra. (e–k) The 2D electric-field distributions on the plane 0.5 mm above the MIM ring resonator at the resonant frequencies marked by M1-M7, which are located at 3.87, 7.89, 9.97, 11.4, 12.13, 13.02, and 13.4 GHz.
Mentions: Figure 4(a) depicts the schematic configuration of the proposed ultrathin corrugated MIM ring resonator, which is composed of two closed corrugated metal strips. The parameters of the inner corrugated metallic disk are the same as those of the disk in Fig. 1(a). The outer radius R1 and the inner radius R2 of the opposite closed corrugated metal are set to be 9 mm and 6 mm, respectively. The groove depth, groove period and groove width of the outer closed corrugated metal grating are denoted by h1, p1, a1, and they are set to be h1 = h = 3 mm, p1 = 2πR1/N = 0.94 mm, and a1 = 0.4p1. Both the width w and the length l of the whole structure are 25 mm. The width g of the air is optimized to 1 mm. The optimization mechanism will be discussed in the later section. Figure 4(b) provides the simulated ECS spectrum of the ultrathin corrugated MIM ring resonator under the excitation of a plane wave, where marked M1-M4 peaks correspond to multiple plasmonic resonances with the dipole, quadrupole, hexapole, and octopole modes at frequencies 3.64, 6.31, 9.55, and 11.71 GHz, respectively. To excite the spoof LSPs by use of a monopole source, the monopole should be parallel to the structure surface, as depicted in Fig. 4(c), to make sure that the magnetic field generated by the monopole source is perpendicular to the structure surface. Hence the magnetic field matches that of spoof LSPs in the corrugated ring structure. The near-field response is plotted in Fig. 4(d), in which seven peaks M1-M7 located at 3.87, 7.89, 9.97, 11.4, 12.13, 13.02, and 13.4 GHz can be observed. Several conclusions can be drawn by comparing Fig. 4 with Fig. 1. First, more resonance modes in the corrugated MIM ring resonator can be observed, no matter a plane wave or a monopole source is used to excite spoof LSPs. The result verifies the theoretical analysis in Fig. 2(c,d). Second, the resonances have been enhanced, which is consistent with the analysis in Fig. 3(c–e). For example, for the case under the excitation of a plane wave, Q factor of M1 resonance peak has been increased a little, changing from 2.7 to 4.2. For the case under the excitation of a monopole source, the dipole resonance is obviously enhanced, although its Q factor is still only 3.17. Q factor of M4 resonance peak has been increased from 40.4 to 54.28. Third, spoof LSPs in the corrugated MIM ring structure are actually standing surface waves31. To form resonances in the circular resonator, the well-known requirement to be satisfied is L = nλg, where L is the circumference of the circular resonator, λg is the guided wavelength on the straight corrugated MIM waveguide, and n is a positive integer. Since groove width of the corrugated MIM ring resonator is non-uniform, we choose a medium groove width to check whether the above relation is satisfied. Hence L = 2πR2 = 37.7 mm and the groove width is a2 = 0.4p2, where p2 = 2πR2/N = 0.63 mm. The wavelength at the resonant modes marked by M1-M7 can be calculated by λg = 2π/β. The calculated results are λgM1 = 39.1 mm, λgM2 = 17.2 mm, λgM3 = 12.2 mm, λgM4 = 9.3 mm, λgM5 = 8.0 mm, λgM6 = 6.6 mm, and λgM7 = 6.0 mm. It can be verified that the circumference L approximately satisfy L ≈ Mi × λgMi, (i = 1, 2, 3……). Lastly, comparing Fig. 4(d) with Fig. 4(b), we can see that the higher modes are also difficult to excite by a plane wave due to the low matching between the field of the plane wave and that of the spoof LSPs for higher resonant modes. In order to verify the multipolar spoof LSPs resonant modes on the corrugated MIM structure excited by the monopole antenna, 2D distributions of electric-field (z-components) on the plane 0.5 mm above the corrugated MIM ring resonator at the resonant frequencies are illustrated in Fig. 4(e–k), where the color scale ranges from red (the highest positive intensity) to blue (the lowest negative intensity). It can be seen that all the resonance modes at M1-M7 can be recognized, while the field patterns in M6 and M7 are not clearly observable.

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.