Asymmetric transmission of terahertz waves using polar dielectrics

Asymmetric wave transmission is a Lorentz reciprocal phenomenon, which can appear in the structures with broken symmetry. It may enable high forward-to-backward transmittance contrast, while transmission for one of the two opposite incidence directions is blocked. In this paper, it is demonstrated that ultrawideband, high-contrast asymmetric wave transmission can be obtained at terahertz frequencies in the topologically simple, i.e., one- or two-layer nonsymmetric gratings, which are entirely or partially made of a polar dielectric working in the ultralow-ε regime inspired by phonon-photon coupling. A variety of polar dielectrics with different characteristics can be used that gives one a big freedom concerning design. Simple criteria for estimating possible usefulness of a certain polar dielectric are suggested. Contrasts exceeding 80dB can be easily achieved without a special parameter adjustment. Stacking a high-ε corrugated layer with a noncorrugated layer made of a polar dielectric, one can enhance transmission in the unidirectional regime. At large and intermediate angles of incidence, a better performance can be obtained owing to the common effect of nonsymmetric diffractions and directional selectivity, which is connected with the dispersion of the ultralow-ε material. At normal incidence, strong asymmetry in transmission may occur in the studied structures as a purely diffraction effect. © 2014 Optical Society of America.

DDC Class

500: Naturwissenschaften

600: Technik

620: Ingenieurwissenschaften

Funding Organisations

TUBITAK

North Atlantic Treaty Organization (NATO), Science and Technology Organization

Matsumae International Foundation (MIF), Japan

Turkish Academy of Sciences

More Funding Information

This work is supported by the projects DPT-HAMIT, ESF-EPIGRAT, NATO-SET-181, and by TUBITAK under Project Nos., 107A004, 109A015, 109E301. Contribution of A.E.S. has partially been supported by the Matsumae International Foundation (MIF), Japan under Research Fellowship Program. E.O. acknowledges partial support from the Turkish Academy of Sciences.

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Asymmetric transmission of terahertz waves using polar dielectrics