Khalichi, BahramGhobadi, AmirOsgouei, Ataollah KalantariÖzbay, Ekmel2022-02-092022-02-092021-06-250022-3727http://hdl.handle.net/11693/77148We present a narrow-band optical diode with a high-contrast forward-to-backward ratio at the near-infrared region. The design has a forward transmission of approximately $88\% $, and a backward one of less than $3\% $, yielding a contrast ratio of greater than $14.5\,$ dB at a wavelength of $1550\,$ nm. The structure is composed of a one-dimensional diffraction grating on top of a dielectric slab waveguide, both of which are made of silicon nitride (Si3N4), and all together are placed over a silver (Ag) thin film embedded on a dielectric substrate. Utilizing a dielectric-based diffraction grating waveguide on a thin silver layer leads to the simultaneous excitation of two surface plasmon modes known as long- and short-range surface plasmon polaritons (SPPs) at both interfaces of the metallic layer. The plasmon-tunneling effect, which is the result of the coupling of SPPs excited at the upper interface of the metallic layer to the radiation modes, provides a high asymmetric transmission (AT) property. The spectral response of the proposed high-contrast AT device is verified using both rigorous coupled-wave analysis as an analytical approach and finite difference time domain as a numerical one.EnglishAsymmetric transmissionDiffraction gratingSurface plasmon polaritonsPlasmon tunnelingArticle10.1088/1361-6463/ac0ab81361-6463