Highly one-way electromagnetic wave transmission based on outcoupling of surface plasmon polaritons to radiation modes

Unidirectional transmission of electromagnetic waves has attracted great interest due to its wide modern optical applications. This study theoretically demonstrates a one-way transmissive optical device with a high-contrast forward-to-backward ratio at the near-infrared region. The polarization-independent optical diode-like mechanism is designed using a metasurface diffraction grating configuration with symmetry breaking property along the wave propagation in which the working principle is based on the excitation of surface plasmon modes at the interfaces of thin metallic interlayer and their coupling to the radiation modes.