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Title: Tunable unidirectional surface plasmon polaritons at the interface between gyrotropic and isotropic conductors

Unidirectionally propagated electromagnetic waves are rare in nature but heavily sought after due to their potential applications in backscatter-free optical information processing setups. It was theoretically shown that the distinct bulk optical band topologies of a gyrotropic metal and an isotropic metal can enable topologically protected unidirectional surface plasmon polaritons (SPPs) at their interface. Here, we experimentally identify such interfacial modes at terahertz frequencies. Launching the interfacial SPPs via a tailored grating coupler, the far-field spectroscopy data obtained reveals strongly nonreciprocal SPP dispersions that are highly consistent with the theoretical predictions. The directionality of the interfacial SPPs studied here is flexibly tunable by either varying the external field or adjusting the metallic characteristics of the bulk materials. The experimental realization of actively tunable unidirectional SPPs sets the foundation for developing nanophotonic information processing devices based on topologically protected interfacial waves.

 
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Award ID(s):
1741673
NSF-PAR ID:
10252172
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
Optical Society of America
Date Published:
Journal Name:
Optica
Volume:
8
Issue:
7
ISSN:
2334-2536
Page Range / eLocation ID:
Article No. 952
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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    Acknowledgment

    This work was partially supported by the U.S. National Science Foundation (NSF) Award No. ECCS-1931088. S.L. and H.W.S. acknowledge the support from the Improvement of Measurement Standards and Technology for Mechanical Metrology (Grant No. 22011044) by KRISS.

    Figure 1

     

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