Diode like high-contrast asymmetric transmission of linearly polarized waves based on plasmon-tunneling effect coupling to electromagnetic radiation modes

Date
2021-06-25
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Source Title
Journal of Physics D: Applied Physics
Print ISSN
0022-3727
Electronic ISSN
1361-6463
Publisher
Institute of Physics Publishing Ltd.
Volume
54
Issue
36
Pages
1 - 12
Language
English
Type
Article
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Abstract

We 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.

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Keywords
Asymmetric transmission, Diffraction grating, Surface plasmon polaritons, Plasmon tunneling
Citation
Published Version (Please cite this version)