Limits...
Demonstration of a Three-dimensional Negative Index Medium Operated at Multiple-angle Incidences by Monolithic Metallic Hemispherical Shells

View Article: PubMed Central - PubMed

ABSTRACT

We design and construct a three-dimensional (3D) negative index medium (NIM) composed of gold hemispherical shells to supplant an integration of a split-ring resonator and a discrete plasmonic wire for both negative permeability and permittivity at THz gap. With the proposed highly symmetric gold hemispherical shells, the negative index is preserved at multiple incident angles ranging from 0° to 85° for both TE and TM waves, which is further evidenced by negative phase flows in animated field distributions and outweighs conventional fishnet structures with operating frequency shifts when varying incident angles. Finally, the fabrication of the gold hemispherical shells is facilitated via standard UV lithographic and isotropic wet etching processes and characterized by μ-FTIR. The measurement results agree the simulated ones very well.

No MeSH data available.


Retrieval results and surface current distributions of the shell.(a) Retrieved permittivity, permeability and (b) index of the gold hemispherical shell. (c) Side-view (x-z plane) and (d) top-view (x-y plane) of surface currents on the shell. A current loop at the bottom in (c) suggests a negative magnetic dipole, m; meanwhile, surface currents along the edge of the shell in (d) induce a negative electric dipole, P.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5384282&req=5

f3: Retrieval results and surface current distributions of the shell.(a) Retrieved permittivity, permeability and (b) index of the gold hemispherical shell. (c) Side-view (x-z plane) and (d) top-view (x-y plane) of surface currents on the shell. A current loop at the bottom in (c) suggests a negative magnetic dipole, m; meanwhile, surface currents along the edge of the shell in (d) induce a negative electric dipole, P.

Mentions: To certify our prediction, the corresponding constitutive parameters are retrieved to verify the existence of the double negative identities, i.e., a negative index18 as shown in Fig. 3(a,b). Figure 3(a) reveals a Drude-model-like behavior of an electric resonance, i.e., negative permittivity before 1.193 THz and anti-resonance at 1.149 THz due to finite spatial periodicity22; in contrast, the occurrence of magnetic resonances forms a Lorentz model resonance and reveals negative permeability between the frequencies of 1.156 THz and 1.177 THz. These double negative identities result in a negative index at the similar frequency regime as highlighted by a green area in Fig. 3(b) which overlaps with the frequency range of the transmission maximum where both permittivity and permeability are negative. The coincidence of the negative index band and the transmission maximum confirms our abovementioned expectation23 and herein we affirm that a transmission apex gradually elevating from a dip is our indicator for a negative index.


Demonstration of a Three-dimensional Negative Index Medium Operated at Multiple-angle Incidences by Monolithic Metallic Hemispherical Shells
Retrieval results and surface current distributions of the shell.(a) Retrieved permittivity, permeability and (b) index of the gold hemispherical shell. (c) Side-view (x-z plane) and (d) top-view (x-y plane) of surface currents on the shell. A current loop at the bottom in (c) suggests a negative magnetic dipole, m; meanwhile, surface currents along the edge of the shell in (d) induce a negative electric dipole, P.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5384282&req=5

f3: Retrieval results and surface current distributions of the shell.(a) Retrieved permittivity, permeability and (b) index of the gold hemispherical shell. (c) Side-view (x-z plane) and (d) top-view (x-y plane) of surface currents on the shell. A current loop at the bottom in (c) suggests a negative magnetic dipole, m; meanwhile, surface currents along the edge of the shell in (d) induce a negative electric dipole, P.
Mentions: To certify our prediction, the corresponding constitutive parameters are retrieved to verify the existence of the double negative identities, i.e., a negative index18 as shown in Fig. 3(a,b). Figure 3(a) reveals a Drude-model-like behavior of an electric resonance, i.e., negative permittivity before 1.193 THz and anti-resonance at 1.149 THz due to finite spatial periodicity22; in contrast, the occurrence of magnetic resonances forms a Lorentz model resonance and reveals negative permeability between the frequencies of 1.156 THz and 1.177 THz. These double negative identities result in a negative index at the similar frequency regime as highlighted by a green area in Fig. 3(b) which overlaps with the frequency range of the transmission maximum where both permittivity and permeability are negative. The coincidence of the negative index band and the transmission maximum confirms our abovementioned expectation23 and herein we affirm that a transmission apex gradually elevating from a dip is our indicator for a negative index.

View Article: PubMed Central - PubMed

ABSTRACT

We design and construct a three-dimensional (3D) negative index medium (NIM) composed of gold hemispherical shells to supplant an integration of a split-ring resonator and a discrete plasmonic wire for both negative permeability and permittivity at THz gap. With the proposed highly symmetric gold hemispherical shells, the negative index is preserved at multiple incident angles ranging from 0° to 85° for both TE and TM waves, which is further evidenced by negative phase flows in animated field distributions and outweighs conventional fishnet structures with operating frequency shifts when varying incident angles. Finally, the fabrication of the gold hemispherical shells is facilitated via standard UV lithographic and isotropic wet etching processes and characterized by μ-FTIR. The measurement results agree the simulated ones very well.

No MeSH data available.