Diode like high-contrast asymmetric transmission of linearly polarized waves based on plasmon-tunneling effect coupling to electromagnetic radiation modes. (25th June 2021)

• Record Type: Journal Article
• Authors: Khalichi, Bahram; Ghobadi, Amir; Kalantari Osgouei, Ataollah; Ozbay, Ekmel
• Is Part Of: Journal of physics. Volume 54:Number 36(2021)
• Publication Date: 2021-06-25
• Subjects: asymmetric transmission -- diffraction grating -- surface plasmon polaritons -- plasmon tunneling; Physics -- Periodicals; 530
• DOI: 10.1088/1361-6463/ac0ab8
• Languages: English
• ISSNs: 0022-3727

Abstract

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 (Si3 N4 ), 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.