By taking advantage of dielectric metasurfaces and plasmonic nanostructures, a terahertz photoconductive antenna (THz-PCA) is proposed and investigated in detail. The designed dielectric metasurfaces can reduce the optical reflection down to 1.4% and accelerate the switching process (electric conductive to resistive) that broadens the THz spectrum emitted from THz-PCA. Simultaneously, the embedded plasmonic nanostructures can realize 11.2 times enhancement in local electric field without affecting the switching process and the damage threshold of the THz-PCA. Simulated results indicate that the proposed THz-PCA is 70.56 times stronger in THz radiation power than that of the traditional THz-PCA. The significant enhancement ensures the proposed THz-PCA has great prospects in promoting THz technology based on the THz-PCA.
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http://dx.doi.org/10.1364/AO.431678 | DOI Listing |
Sci Rep
January 2025
School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China.
In recent years, research on chiral bound states in the continuum (BIC) has surged, leading to the development of various chiral metasurfaces with narrow bandwidths by breaking of in-plane and out-of-plane symmetries. However, the ability to dynamically tune the working band remains relatively unexplored, which is valuable for chiral sensing applications. Optical phase-change materials, with tunable dielectric constants and switchable properties during phase transition, offer the potential for dynamic control of optical metasurfaces.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
RIKEN Center for Advanced Photonics, RIKEN, 519-1399 Aramaki-Aoba, Sendai, Miyagi, 980-0845, Japan.
This study presents a generalized design strategy for novel terahertz-wave polarization space-division multiplexing meta-devices, functioning as multi-polarization generators, modulators, and analyzers. It introduces the spin-decoupled phase control method by combining gradient phase design with circular polarization multiplexing techniques, enabling exceptional flexibility in controlling the polarization directions and spatial distributions of multiple output beams. The meta-device M-4D is significantly demonstrated as proof of concept, which converts an incident linearly polarized wave into four beams with distinct polarization angles.
View Article and Find Full Text PDFBiosensors (Basel)
December 2024
School of Integrated Circuits, Shandong University, Jinan 250100, China.
Terahertz (THz) spectroscopy, an advanced label-free sensing method, offers significant potential for biomolecular detection and quantitative analysis in biological samples. Although broadband fingerprint enhancement compensates for limitations in detection capability and sensitivity, the complex optical path design in operation restricts its broader adoption. This paper proposes a multi-degree-of-freedom stretchable metasurface that supports magnetic dipole resonance to enhance the broadband THz fingerprint detection of trace analytes.
View Article and Find Full Text PDFAll-dielectric metasurface (ADM) absorbers driven by quasi-bound states in the continuum (BIC) are critical for high-performance optoelectronic devices due to their ability to offer high -factor absorption. However, these all-dielectric metasurfaces usually require the aid of degenerate critical coupling schemes or back-metal reflective layers to achieve high absorption, which often suffers from limitations such as sensitive geometrical parameters, ohmic losses, and low -factors. This work presents an ADM for high- near-perfect light absorption, which consists of double Si nanorods and SiO/TaO multilayers.
View Article and Find Full Text PDFNanophotonics
April 2024
Department of Bio-Functions and Systems Science, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588 Japan.
Metasurface holograms offer various advantages, including wide viewing angle, small volume, and high resolution. However, full-color animation of high-resolution images has been a challenging issue. In this study, a full-color dielectric metasurface holographic movie with a resolution of 2322 × 2322 was achieved by spatiotemporally multiplexing 30 frames with blue, green, and red color channels at the wavelengths of 445 nm, 532 nm, and 633 nm at the maximum reconstruction speed of 55.
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