Entwurf passiver Einweg-Bauelemente für Ein- und Multistrahl-Betrieb bei Mikrowellen mittels Photonischer Kristalle mit strukturierten Grenzflächen und reduzierter Symmetrie
Zusammenfassung der Projektergebnisse
In the frame of this project, the potential of nonsymmetric structures based on photonic crystals and metamaterials in achieving of unidirectional Lorentz-reciprocal transmission has been studied and (pre-) prototypes of C-, K-, and V-band diodelike devices have been designed and experimentally validated. The main attention has been paid to the photonic crystal gratings that represent arrays of dielectric and metallic rods, with one-side corrugations. The linear, isotropic, passive materials that are commonly used at microwave and millimetre-wave frequencies are only needed. It has been shown that unidirectional splitting and single-beam unidirectional deflection can be obtained in a wide range of variation of geometric, material, and corrugation parameters. The most interesting manifestations of these regimes are connected with reflection-free unidirectional transmission, at which total transmission appears for one of the two opposite directions at the price of deflection from the incidence direction for the corrugated-side illumination, while total reflection occurs for the noncorrugated-side illumination. The observed regime can be interpreted as a perfect Fabry-Perot resonance in the curvilinear transmission channel(s). Alongside the wideband unidirectional transmission that is inspired by the common effect of the specific dispersion of the Floquet-Bloch waves and the peculiar asymmetry in diffraction and coupling at the two opposite interfaces, the inverse regime of asymmetric transmission has been found that may appear only due to diffractions. In this case, strong transmission corresponds to the noncorrugated-side illumination, while transmission is blocked at the corrugated-side illumination. The direct and inverse regimes can co-exist in the same structure that enables reversibility of the diodelike transmission effect. Whereas the rod-array structures for diodelike transmission are typically three free-space wavelengths thick, their analogues based on the stacked hole array metamaterials with the localized hole resonances allow one obtaining performances being thinner than one wavelength. A more careful parameter adjustment is needed for these structures in order to obtain total (reflection-free) transmission for one of the two opposite directions at a reduced total thickness. As an alternative, another mechanism of asymmetric transmission has been studied, which is based on conversion of the incident linear polarization into the orthogonal one, instead of utilizing diffractions. It has been shown that the reflection-free transmission can be obtained in the twisted arrays of subwavelength resonators at the total thickness of λ/10 and smaller. This makes the polarization conversion mechanism especially promising. Additional degree of freedom in terms of directional selectivity has been demonstrated in the nonsymmetric gratings based on photonic crystals with the combined lattice. Owing to the additional symmetry breaking, they enable substantially different transmittances also when changing sign of the incidence angle. As a result, new regimes of directional selectivity can be obtained. Finally, asymmetry between the radiation and penetration (scattering) problems has been studied in the circular-shaped arrays of the rods, with one-side corrugations. Strong difference in the incident wavefronts for these two problems may result in the strong asymmetry, while staying within the Lorentz reciprocal framework. The obtained results can be useful for the future devices that do not need biasing or magnetization. They include direction selective diodelike devices, splitters, deflectors, and radomes that can be used in various applications related to generation and manipulation of electromagnetic waves in the microwave and millimeter-wave frequency ranges.
Projektbezogene Publikationen (Auswahl)
- One-way diffraction effects in photonic crystal gratings made of isotropic materials, Phys. Rev. B, vol. 80, no. 15, 155117, 2009
A. E. Serebryannikov
- Unidirectional transmission using non-symmetric photonic-crystal gratings made of isotropic materials, European Conference on Antennas and Propagation – EuCAP2010, Barcelona, Spain, April 12-16, 2010
A. E. Serebryannikov
- Toward compact millimeter-wave diode in thin stacked-hole array assisted by a dielectric grating, Appl. Phys. Lett., vol. 99, no. 15, 154101, 2011
M. Beruete, A. E. Serebryannikov, V. Torres, M. Navarro-Cia, and M. Sorolla
- Diodelike asymmetric transmission of linearly polarized waves using magnetoelectric coupling and electromagnetic wave tunneling, Phys. Rev. Lett., vol. 108, no. 21, 213905, 2012
M. Mutlu, A. E. Akosman, A. E. Serebryannikov, and E. Ozbay
(Siehe online unter https://doi.org/10.1103/PhysRevLett.108.213905) - Multichannel optical diode with unidirectional diffraction relevant total transmission, Opt. Express, vol. 20, no. 14, pp. 14980-14990, 2012
A. E. Serebryannikov, A. O. Cakmak, and E. Ozbay
(Siehe online unter https://doi.org/10.1364/OE.20.014980) - Experimental study of broadband unidirectional splitting in photonic crystal gratings with broken structural symmetry, Appl. Phys. Lett., vol. 102, no. 15, 151105, 2013
E. Colak, A.E. Serebryannikov, A.O. Cakmak, and E. Ozbay
(Siehe online unter https://doi.org/10.1063/1.4800147)
