Versatile metal-wire waveguides for broadband terahertz signal processing and multiplexing

Abstract

Waveguides play a pivotal role in the full deployment of terahertz communication systems. Besides signal transporting, innovative terahertz waveguides are required to provide versatile signal-processing functionalities. Despite fundamental components, such as Bragg gratings, have been recently realized, they typically rely on complex hybridization, in turn making it extremely challenging to go beyond the most elementary functions. Here, we propose a universal approach, in which multiscale-structured Bragg gratings can be directly etched on metal-wires. Such an approach, in combination with diverse waveguide designs, allows for the realization of a unique platform with remarkable structural simplicity, yet featuring unprecedented signal-processing capabilities. As an example, we introduce a four-wire waveguide geometry, amenable to support the low-loss and low-dispersion propagation of polarization-division multiplexed terahertz signals. Furthermore, by engraving on the wires judiciously designed Bragg gratings based on multiscale structures, it is possible to independently manipulate two polarization-division multiplexed terahertz signals. This platform opens up new exciting perspectives for exploiting the polarization degree of freedom and ultimately boosting the capacity and spectral efficiency of future terahertz networks.

Terahertz Resonances of Transverse Standing Waves in a Corrugated Plate Waveguide

“…Fortunately, periodic waveguide structure with intriguing band gap properties provides an effective way to solve this problem. Such artificial periodic materials are called photonic crystals in optics and has been widely used to develop a variety of optical [39] and THz devices [40], [41]. Most of these bandgaps were essentially identified as being caused by the well-known Bragg resonance, which originates from the strong interference between incident and reflected waves with the same transverse mode.…”

Flexible Terahertz Photonic Light-Cage Modules for In-Core Sensing and High Temperature Applications

“…Single metal wires can guide terahertz radiation via radially polarized surface modes with relatively low loss and in direct contact with the surrounding environment, but the associated coupling efficiency with commonly available systems and confinement characteristics are notoriously poor . However, the low coupling efficiency can be addressed by waveguide-specific concentric antenna designs. , Multiwire waveguides offer an attractive alternative but typically rely on additional support to maintain the desired spacing and configuration , and are often enclosed entirely. ,, …”

“…40 However, the low coupling efficiency can be addressed by waveguide-specific concentric antenna designs. 41,42 Multiwire waveguides 43 offer an attractive alternative but typically rely on additional support to maintain the desired spacing and configuration 43,44 and are often enclosed entirely. 8,22,31 In recent years, an alternative novel hollow-core waveguide has emerged: the so-called "photonic light cage."…”

Terahertz modulation characteristics of three nanosols under external field control based on microfluidic chip

“…Terahertz (THz) wave ( Cong et al., 2021 ; Tseng et al., 2020 ; Zhu et al., 2021 ; Lu et al., 2021 ) refers to an electromagnetic wave with a frequency of 0.1–10 THz and a wavelength of 0.03–3 mm, with a frequency band between millimeter waves and infrared light. Because of their wide bandwidth, low photon energy, and fingerprint spectral properties, THz waves have a wide range of application prospects in basic research fields, such as wireless communication, medical imaging, and biological diagnosis ( Li et al., 2022 ; Jia et al., 2022 ; Dong et al., 2022 ; Wang et al., 2022a , 2022b , 2022c ). Recently, THz sources ( Dong et al., 2021 ) and THz detectors ( Asgari et al., 2021 ) have made great progress, and solid-state THz modulation elements have developed rapidly with the increasing maturity of metasurface technology and semiconductor theory.…”