Modulating extraordinary terahertz transmissions in multilayer plasmonic metasurfaces

Abstract

Manipulations of light–matter interaction via sub-wavelength plasmonic structures have opened up many new research opportunities in photonics from microwave to the visible spectrum, including the relatively underdeveloped but technologically important terahertz regime. Here, we have studied manipulation of terahertz transmission through a bilayer metasurface consisting of a metallic hole array and a complimentary patch array separated by an ultra-thin dielectric spacer. The terahertz transmission spectra through our studied metasurfaces exhibit characteristic resonances due to the surface plasmon induced extraordinary transmission peak. Our study reveals a counterintuitive blue shift of the transmission peak with increasing spacer thickness, which is explained by reduced Coulomb interaction between two plasmonic layers. The measured quality factor exhibits a strong dependence on the spacer thickness, and the maximum quality factor is observed for a spacer thickness of around λ/30, indicating strong electric-field confinement inside the dielectric spacer. These bilayer plasmonic structures will aid in realizing next-generation terahertz plasmonic devices such as ultrasensitive thin-film sensors, modulators, narrow-band filters, and other nonlinear components.

Enhanced extraordinary terahertz transmission through coupling between silicon resonators

“…This process clearly reveals how the electromagnetic wave couples into the particle and radiates to the far field. 37 Therefore, silicon particles can be used as strong magnetic dipole resonators to enhance transmission.…”

“…The process described above leads to an effective increase in the net capacitance of the structure, which shis the resonance peak progressively to the lower side of the frequency spectrum. 37,40,41 It is clearly shown that the Mie resonance structure can be dynamically and continuously modulated using the parameters of dielectric particles.…”

Hybrid resonant cavities: A route towards phase engineered THz metasurfaces

“…This scheme enhances the transmission through the aperture but the tuning of resonance frequency could not be realized by using the metamaterial. Recently, in another work, a bilayer structure consisting of metallic hole array and complementary metamaterial patch array was also demonstrated to manipulate the transmissions through the subwavelength hole arrays (Banerjee et al, 2020). Although this study could demonstrate significant tuning in resonance intensity, tuning of resonance frequency was bare minimum.…”

Polarization-independent tunable terahertz slow light with electromagnetically induced transparency metasurface

“…Fabrication of samples is done on a highly resistive silicon substrate (resistivity > 5000 Ω cm) having a thickness ∼500 μm. First, a positive photoresist is deposited on the polished side of a cleaned silicon wafer ( 100 orientation) with the help of spin coating process [54]. Then, the periodic array of the metasurface is patterned on the photoresist by means of the UV photolithography followed by a development process.…”