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Strong near field enhancement in THz nano-antenna arrays.

Feuillet-Palma C, Todorov Y, Vasanelli A, Sirtori C - Sci Rep (2013)

Bottom Line: In the microwave domain, for many years this task has been successfully performed by antennas, built from metals that can be considered almost perfect at these frequencies.In this work we experimentally study the light coupling properties of dense arrays of subwavelength THz antenna microcavities.This effect is quantitatively described by an analytical model that can be applied for the optimization of any nanoantenna array.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire "Matériaux et Phénomènes Quantiques", Sorbonne Paris Cité, Université Paris Diderot, CNRS-UMR 7162, FR-75013 Paris, France.

ABSTRACT
A key issue in modern photonics is the ability to concentrate light into very small volumes, thus enhancing its interaction with quantum objects of sizes much smaller than the wavelength. In the microwave domain, for many years this task has been successfully performed by antennas, built from metals that can be considered almost perfect at these frequencies. Antenna-like concepts have been recently extended into the THz and up to the visible, however metal losses increase and limit their performances. In this work we experimentally study the light coupling properties of dense arrays of subwavelength THz antenna microcavities. We demonstrate that the combination of array layout with subwavelength electromagnetic confinement allows for 10(4)-fold enhancement of the electromagnetic energy density inside the cavities, despite the low quality factor of a single element. This effect is quantitatively described by an analytical model that can be applied for the optimization of any nanoantenna array.

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Geometrical layout for our model.(a) Schematic of the volume used to express the energy flow conservation in our system. The volume lays on a unit cell of the array. The different Poynting fluxes normal to the surfaces are indicated. (b) Representation of the incoming electric field projection and of the fringing fields for a single resonator. The inset indicates the polar angles describing the direction of the incident plane wave. The parameter a is the typical extension of the fringing fields.
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f6: Geometrical layout for our model.(a) Schematic of the volume used to express the energy flow conservation in our system. The volume lays on a unit cell of the array. The different Poynting fluxes normal to the surfaces are indicated. (b) Representation of the incoming electric field projection and of the fringing fields for a single resonator. The inset indicates the polar angles describing the direction of the incident plane wave. The parameter a is the typical extension of the fringing fields.

Mentions: Here we provide the detailed derivations of Eq.(2) and Eq.(4). The geometry of the model is described in Figure 6. We consider a TM polarized plane wave incident on the array, with an in-plane wavevector G00 with components: Here θ and φ are the polar angles that correspond to the direction of the incoming wave with respect to the resonator axis as defined in Fig. 6. Moreover, we suppose that the field in the resonator is described by the standing wave equation Ez = Ez0cos(xπ/s)19.


Strong near field enhancement in THz nano-antenna arrays.

Feuillet-Palma C, Todorov Y, Vasanelli A, Sirtori C - Sci Rep (2013)

Geometrical layout for our model.(a) Schematic of the volume used to express the energy flow conservation in our system. The volume lays on a unit cell of the array. The different Poynting fluxes normal to the surfaces are indicated. (b) Representation of the incoming electric field projection and of the fringing fields for a single resonator. The inset indicates the polar angles describing the direction of the incident plane wave. The parameter a is the typical extension of the fringing fields.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3584925&req=5

f6: Geometrical layout for our model.(a) Schematic of the volume used to express the energy flow conservation in our system. The volume lays on a unit cell of the array. The different Poynting fluxes normal to the surfaces are indicated. (b) Representation of the incoming electric field projection and of the fringing fields for a single resonator. The inset indicates the polar angles describing the direction of the incident plane wave. The parameter a is the typical extension of the fringing fields.
Mentions: Here we provide the detailed derivations of Eq.(2) and Eq.(4). The geometry of the model is described in Figure 6. We consider a TM polarized plane wave incident on the array, with an in-plane wavevector G00 with components: Here θ and φ are the polar angles that correspond to the direction of the incoming wave with respect to the resonator axis as defined in Fig. 6. Moreover, we suppose that the field in the resonator is described by the standing wave equation Ez = Ez0cos(xπ/s)19.

Bottom Line: In the microwave domain, for many years this task has been successfully performed by antennas, built from metals that can be considered almost perfect at these frequencies.In this work we experimentally study the light coupling properties of dense arrays of subwavelength THz antenna microcavities.This effect is quantitatively described by an analytical model that can be applied for the optimization of any nanoantenna array.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire "Matériaux et Phénomènes Quantiques", Sorbonne Paris Cité, Université Paris Diderot, CNRS-UMR 7162, FR-75013 Paris, France.

ABSTRACT
A key issue in modern photonics is the ability to concentrate light into very small volumes, thus enhancing its interaction with quantum objects of sizes much smaller than the wavelength. In the microwave domain, for many years this task has been successfully performed by antennas, built from metals that can be considered almost perfect at these frequencies. Antenna-like concepts have been recently extended into the THz and up to the visible, however metal losses increase and limit their performances. In this work we experimentally study the light coupling properties of dense arrays of subwavelength THz antenna microcavities. We demonstrate that the combination of array layout with subwavelength electromagnetic confinement allows for 10(4)-fold enhancement of the electromagnetic energy density inside the cavities, despite the low quality factor of a single element. This effect is quantitatively described by an analytical model that can be applied for the optimization of any nanoantenna array.

Show MeSH
Related in: MedlinePlus