Presentation
18 September 2018 Broadband terahertz polarization conversion using metasurfaces (Conference Presentation)
Hou-Tong Chen, Chun-Chieh Chang
Author Affiliations +
Abstract
Two-dimensional metamaterials - metasurfaces - offer tremendous opportunities in realizing exotic optical phenomena and functionalities to address the technological challenges encountered in the terahertz frequency regime. By tailoring the resonant response of basic building blocks as well as their mutual interactions, we are able to effectively control of amplitude, phase, and polarization state of terahertz waves. Here we report the realization of highly efficient polarization conversions including: (1) Reflective linear polarization rotation using an array of anisotropic resonators backed with a ground plane; (2) Transmissive linear polarization rotation using an array of anisotropic resonator array sandwiched by two orthogonal gratings; and (3) Reflective linear-to-circular polarization conversion using two cascading arrays of complementary resonators. They operate over a broad bandwidth more than one octave and approaching two octaves in some cases. We further show that the linear polarization rotation is accompanied by a tunable phase discontinuity, which allows us to demonstrate an ultrathin terahertz flat lens enabling diffraction-limited focusing. The broadband linear-to-circular polarization may also find applications including terahertz circular dichroism spectroscopy and excitation of valley polarization in 2D materials.
Conference Presentation
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Hou-Tong Chen and Chun-Chieh Chang "Broadband terahertz polarization conversion using metasurfaces (Conference Presentation)", Proc. SPIE 10756, Terahertz Emitters, Receivers, and Applications IX, 107560C (18 September 2018); https://doi.org/10.1117/12.2322496
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KEYWORDS
Polarization

Resonators

Reflectivity

Circular dichroism spectroscopy

Metamaterials

Optical properties

Terahertz radiation

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