Octave-Spanning Terahertz Quarter-Wave Plates Based on Over-Coupled Fabry-Pérot Resonances in Reflective Metal-Dielectric-Metal Metasurfaces

Fuente: arXiv
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Auteurs principaux: Park, Tae Gwan, Chang, Chun-Chieh, Taylor, Antoinette J., Azad, Abul K., Chen, Hou-Tong
Format: Preprint
Publié: 2026
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author Park, Tae Gwan
Chang, Chun-Chieh
Taylor, Antoinette J.
Azad, Abul K.
Chen, Hou-Tong
author_facet Park, Tae Gwan
Chang, Chun-Chieh
Taylor, Antoinette J.
Azad, Abul K.
Chen, Hou-Tong
contents Compact devices for broadband polarization control in the terahertz (THz) regime are challenging due to the intrinsic phase dispersion of birefringent materials and resonant structures. Here, we demonstrate high-performance broadband THz quarter-wave plates based on over-coupled metal-dielectric-metal reflective metasurfaces. The devices operate as single-port anisotropic Fabry-Pérot cavities in which the phase dispersion of over-coupled resonances is engineered to produce an approximately constant relative phase delay between orthogonal field components. By tailoring the metasurface geometry, efficient linear-to-circular polarization conversion is achieved while maintaining high reflectance. Four complementary metasurface designs, operated at an incidence angle of $45^\circ$, collectively cover the 0.25--3 THz frequency range accessible to a typical THz time-domain spectroscopy system. Each device exhibits an approximately octave-wide bandwidth with an axial ratio below 3\,dB and polarization conversion efficiencies exceeding 80\% across most of the operating band. Systematic optimization suppresses coupling to higher-order diffraction and surface wave modes, further extending the usable bandwidth while preserving the required phase relationship. The metasurfaces are compatible with wafer-scale fabrication, and experimental results show excellent agreement with simulations. These findings establish over-coupled reflective metasurfaces as a robust and versatile platform for broadband THz polarization control.
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id arxiv_https___arxiv_org_abs_2604_03487
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Octave-Spanning Terahertz Quarter-Wave Plates Based on Over-Coupled Fabry-Pérot Resonances in Reflective Metal-Dielectric-Metal Metasurfaces
Park, Tae Gwan
Chang, Chun-Chieh
Taylor, Antoinette J.
Azad, Abul K.
Chen, Hou-Tong
Optics
Applied Physics
Compact devices for broadband polarization control in the terahertz (THz) regime are challenging due to the intrinsic phase dispersion of birefringent materials and resonant structures. Here, we demonstrate high-performance broadband THz quarter-wave plates based on over-coupled metal-dielectric-metal reflective metasurfaces. The devices operate as single-port anisotropic Fabry-Pérot cavities in which the phase dispersion of over-coupled resonances is engineered to produce an approximately constant relative phase delay between orthogonal field components. By tailoring the metasurface geometry, efficient linear-to-circular polarization conversion is achieved while maintaining high reflectance. Four complementary metasurface designs, operated at an incidence angle of $45^\circ$, collectively cover the 0.25--3 THz frequency range accessible to a typical THz time-domain spectroscopy system. Each device exhibits an approximately octave-wide bandwidth with an axial ratio below 3\,dB and polarization conversion efficiencies exceeding 80\% across most of the operating band. Systematic optimization suppresses coupling to higher-order diffraction and surface wave modes, further extending the usable bandwidth while preserving the required phase relationship. The metasurfaces are compatible with wafer-scale fabrication, and experimental results show excellent agreement with simulations. These findings establish over-coupled reflective metasurfaces as a robust and versatile platform for broadband THz polarization control.
title Octave-Spanning Terahertz Quarter-Wave Plates Based on Over-Coupled Fabry-Pérot Resonances in Reflective Metal-Dielectric-Metal Metasurfaces
topic Optics
Applied Physics
url https://arxiv.org/abs/2604.03487