TY - JOUR

T1 - Theory of dielectric photonic crystals sandwiched between parallel metal plates

AU - Bendtsen, Reiko Inoue

AU - Skovsen, Esben

AU - Søndergaard, Thomas Møller

N1 - © 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement
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PY - 2023/2/15

Y1 - 2023/2/15

N2 - Photonic crystals based on silicon-air-geometries sandwiched between parallel metal plates are studied theoretically. Compared with in-plane propagation in corresponding infinite-height photonic crystals, modes with one of the two possible polarizations are eliminated for small plate separations. Consequently, 2D photonic crystals that usually do not have a band gap for both polarizations possess a complete band gap in the sandwich geometry. A procedure for obtaining the maximum allowed photonic-crystal height between plates that preserves the in-plane band gap is described. The effect on the band gap of adding an air-gap or a silicon substrate to the photonic crystal structure between plates is also studied. Finally, it is shown that, for terahertz frequencies, a useful distance between metal plates is comparable to the thickness of thin silicon wafers, and that propagation losses are sufficiently small that the structures are of practical interest. We briefly discuss the numerical method that was used for calculating band diagrams and band gaps, which is based on a modification to the plane-wave-expansion method [R. D. Meade et. al., Phys. Rev. B 48, 8434 (1993)] based on an iterative search algorithm exploiting Fast Fourier Transforms for fast calculations.

AB - Photonic crystals based on silicon-air-geometries sandwiched between parallel metal plates are studied theoretically. Compared with in-plane propagation in corresponding infinite-height photonic crystals, modes with one of the two possible polarizations are eliminated for small plate separations. Consequently, 2D photonic crystals that usually do not have a band gap for both polarizations possess a complete band gap in the sandwich geometry. A procedure for obtaining the maximum allowed photonic-crystal height between plates that preserves the in-plane band gap is described. The effect on the band gap of adding an air-gap or a silicon substrate to the photonic crystal structure between plates is also studied. Finally, it is shown that, for terahertz frequencies, a useful distance between metal plates is comparable to the thickness of thin silicon wafers, and that propagation losses are sufficiently small that the structures are of practical interest. We briefly discuss the numerical method that was used for calculating band diagrams and band gaps, which is based on a modification to the plane-wave-expansion method [R. D. Meade et. al., Phys. Rev. B 48, 8434 (1993)] based on an iterative search algorithm exploiting Fast Fourier Transforms for fast calculations.

UR - http://www.scopus.com/inward/record.url?scp=85167679416&partnerID=8YFLogxK

U2 - 10.1364/OPTCON.472541

DO - 10.1364/OPTCON.472541

M3 - Journal article

VL - 2

SP - 312

EP - 326

JO - Optics Continuum

JF - Optics Continuum

IS - 2

ER -