January 27, 2023

Unidirectional excitation of metamaterial interface waveguides; the chirality of the source determines the direction of the energy flow along the edge. Credit: Zhixia Xu

Metamaterial interface waveguides can confine and conduct electromagnetic (EM) waves, which has attractive potential in integrated photonics physics and wireless devices, from radio frequencies to optical bands. The energy flow in waveguides can be fully controlled by sorting the light waves in the near field by their handedness (chirality), which determines the direction of energy transmission. Chirality sorting is an important process to develop in the field of chiral photonics. In the future, chiral-sorting metadevices can be fully digitized and programmable, so that reconfigurable unidirectional transmission routes and scattering performance of the artificial structures can be controlled simultaneously.

To get there, we need to better understand the features and possible applications of different edge modes. As reported in Advanced Photonicsresearchers from Southeast University, Dalian Maritime University and the University of California at San Diego collaborated to visualize different unidirectional fringe waves in microwave-metamaterial interface waveguides, based on localized sources carrying spin angular momentum and orbital angular momentum.

In their work, they present a local light source composed of an electrical probe array. Their design includes a broadband power network to ensure the angular momentum performance of the light rays. For their systematic experiments, they set up a near-field scanning platform to directly measure the unidirectional transmission. Based on their observations of three edge states – spoof plasmon polaritons, line waves, and valley topological insulators – they assess the advantages and disadvantages of each.

Chiral Sources for Metamaterial Interface Waveguides

Unidirectional excitation of various waveguides with metamaterial interface. (a) Sources of angular momentum. (b) SSPPs (±εeff). (c) LWs (± Zsurf). (d) Valley PTIs (±ФBerry). Credit: Xu et al., DOI: 10.1117/1.AP.4.4.046004

Overall, this research advances the field of chiral photonics science and advances applications of chiral sorting technology, especially for microwave metdevices. According to corresponding author Tie Jun Cui of the State Key Laboratory of Millimeter Waves at Southeast University in Nanjing, “Developing the freedom of microwave angular momentum in the waveguides makes sense to increase channel capacitance and design robust and flexible devices. Based on various metamaterial interface waveguides, new meta-devices such as filters, splitters, antennas and multiplexers can be widely used in radar and communication systems.”

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More information:
Zhixia Xu et al, Near-field chiral excitation of universal spin-momentum locking transport of fringe waves in microwave metamaterials, Advanced Photonics (2022). DOI: 10.1117/1.AP.4.4.046004

Quote: Chiral Sources for Metamaterial Interface Waveguides (2022, July 19) retrieved July 19, 2022 from https://phys.org/news/2022-07-chiral-sources-metamaterial-interface-waveguides.html

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