Topological refraction in dual-band valley sonic crystals

Valley pseudospins, as quantum states of energy extrema in momentum space, have been introduced from condensed-matter systems into classical sound systems, and several valley sonic crystals (VSCs) have been realized experimentally. However, in the existing VSCs, topological kink states generally app...

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Main Authors: Jia, Ding, Ge, Yong, Xue, Haoran, Yuan, Shou-qi, Sun, Hong-xiang, Yang, Yihao, Liu, Xiao-jun, Zhang, Baile
Other Authors: School of Physical and Mathematical Sciences
Format: Article
Language:English
Published: 2021
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Online Access:https://hdl.handle.net/10356/151103
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Institution: Nanyang Technological University
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spelling sg-ntu-dr.10356-1511032023-02-28T19:56:31Z Topological refraction in dual-band valley sonic crystals Jia, Ding Ge, Yong Xue, Haoran Yuan, Shou-qi Sun, Hong-xiang Yang, Yihao Liu, Xiao-jun Zhang, Baile School of Physical and Mathematical Sciences Centre for Disruptive Photonic Technologies (CDPT) The Photonics Institute Science::Physics Acoustic Wave Phenomena Acoustics Valley pseudospins, as quantum states of energy extrema in momentum space, have been introduced from condensed-matter systems into classical sound systems, and several valley sonic crystals (VSCs) have been realized experimentally. However, in the existing VSCs, topological kink states generally appear in a single band gap, which apparently has become an obstacle for multiband topological sound devices. To overcome this challenge, we here experimentally demonstrate dual-band VSCs, in which robust valley kink states exist in two separated bulk band gaps. More interestingly, two opposite valleys separately located in two band gaps are locked to a single propagation direction, which arises from the fact that the bands below two band gaps show opposite valley Chern numbers at the K/K′ valley. This double valley-locking phenomenon has been demonstrated via measuring the topological refraction of the kink states into the ambient space at a zigzag termination. We observe positive refraction at the lower band gap, whereas the coexistence of positive and negative refraction at the higher band gap. Additionally, we observe the robust valley transport through the sharp corners at two band gaps. The designed VSCs with the dual-band topological refraction and robust valley transport could find potential applications in multiband and multidirectional devices. Ministry of Education (MOE) Published version This work was supported by the National Natural Science Foundation of China (Grants No. 11774137, No. 51779107, and No. 11834008), the National Key R&D Program of China (Grants No. 2020YFC1512400 and No. 2020YFC1512403), the Singapore Ministry of Education [Grants No. MOE2018-T2-1-022 (S), No. MOE2016-T3-1-006, and Tier 1 RG174/16 (S)], State Key Laboratory of Acoustics, Chinese Academy of Science (Grant No. SKLA202016), and the China Postdoctoral Science Foundation (Grant No. 2020M671351). 2021-06-29T02:14:05Z 2021-06-29T02:14:05Z 2021 Journal Article Jia, D., Ge, Y., Xue, H., Yuan, S., Sun, H., Yang, Y., Liu, X. & Zhang, B. (2021). Topological refraction in dual-band valley sonic crystals. Physical Review B, 103(14), 144309-. https://dx.doi.org/10.1103/PhysRevB.103.144309 2469-9950 https://hdl.handle.net/10356/151103 10.1103/PhysRevB.103.144309 2-s2.0-85105077762 14 103 144309 en MOE2018-T2-1-022 (S) MOE2016-T3-1-006 RG174/16 (S) Physical Review B 10.21979/N9/NYNIWR © 2021 American Physical Society (APS). All rights reserved. This paper was published in Physical Review B and is made available with permission of American Physical Society (APS). application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Science::Physics
Acoustic Wave Phenomena
Acoustics
spellingShingle Science::Physics
Acoustic Wave Phenomena
Acoustics
Jia, Ding
Ge, Yong
Xue, Haoran
Yuan, Shou-qi
Sun, Hong-xiang
Yang, Yihao
Liu, Xiao-jun
Zhang, Baile
Topological refraction in dual-band valley sonic crystals
description Valley pseudospins, as quantum states of energy extrema in momentum space, have been introduced from condensed-matter systems into classical sound systems, and several valley sonic crystals (VSCs) have been realized experimentally. However, in the existing VSCs, topological kink states generally appear in a single band gap, which apparently has become an obstacle for multiband topological sound devices. To overcome this challenge, we here experimentally demonstrate dual-band VSCs, in which robust valley kink states exist in two separated bulk band gaps. More interestingly, two opposite valleys separately located in two band gaps are locked to a single propagation direction, which arises from the fact that the bands below two band gaps show opposite valley Chern numbers at the K/K′ valley. This double valley-locking phenomenon has been demonstrated via measuring the topological refraction of the kink states into the ambient space at a zigzag termination. We observe positive refraction at the lower band gap, whereas the coexistence of positive and negative refraction at the higher band gap. Additionally, we observe the robust valley transport through the sharp corners at two band gaps. The designed VSCs with the dual-band topological refraction and robust valley transport could find potential applications in multiband and multidirectional devices.
author2 School of Physical and Mathematical Sciences
author_facet School of Physical and Mathematical Sciences
Jia, Ding
Ge, Yong
Xue, Haoran
Yuan, Shou-qi
Sun, Hong-xiang
Yang, Yihao
Liu, Xiao-jun
Zhang, Baile
format Article
author Jia, Ding
Ge, Yong
Xue, Haoran
Yuan, Shou-qi
Sun, Hong-xiang
Yang, Yihao
Liu, Xiao-jun
Zhang, Baile
author_sort Jia, Ding
title Topological refraction in dual-band valley sonic crystals
title_short Topological refraction in dual-band valley sonic crystals
title_full Topological refraction in dual-band valley sonic crystals
title_fullStr Topological refraction in dual-band valley sonic crystals
title_full_unstemmed Topological refraction in dual-band valley sonic crystals
title_sort topological refraction in dual-band valley sonic crystals
publishDate 2021
url https://hdl.handle.net/10356/151103
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