Valley-Hall photonic crystal waveguides under non-Hermitian active defect

Photonic transport facilitated by topological protection is a proposed advantage of photonic topological waveguides based on valley photonic crystals (VPCs). Although topological protection significantly suppresses backscattering in these waveguides, it is often desirable to achieve active control o...

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Main Authors: Jayaram, Shrinivas, Tan, Yi Ji, Navaratna, Nikhil, Tan, Thomas CaiWei, Chong, Yidong, Singh, Ranjan
Other Authors: School of Physical and Mathematical Sciences
Format: Article
Language:English
Published: 2024
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Online Access:https://hdl.handle.net/10356/180487
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1804872024-10-14T15:35:21Z Valley-Hall photonic crystal waveguides under non-Hermitian active defect Jayaram, Shrinivas Tan, Yi Ji Navaratna, Nikhil Tan, Thomas CaiWei Chong, Yidong Singh, Ranjan School of Physical and Mathematical Sciences Centre for Disruptive Photonic Technologies (CDPT) The Photonics Institute Physics Crystal waveguides Hermitians Photonic transport facilitated by topological protection is a proposed advantage of photonic topological waveguides based on valley photonic crystals (VPCs). Although topological protection significantly suppresses backscattering in these waveguides, it is often desirable to achieve active control over the transmission characteristics. We utilize photoexcited carriers in silicon to implement an active defect—a local, actively tunable, dissipative non-Hermitian perturbation in the path of a terahertz VPC waveguide—and systematically characterize the transport characteristics. We study waveguides constructed from different VPC interfaces (zigzag and bearded) and show that the high group index VPC waveguide modes are more strongly modulated by the phototunable defect. In both the waveguides, the faster modes exhibit approximately linear variation in transmission loss with increase in defect through enhanced photocarrier generation. However, for slower modes, the transmission loss varies nonlinearly, indicative of enhanced interaction with the active defect. We are able to model this behavior in terms of a group delay dependent loss. Our study not only highlights the superior performance of low index VPC waveguide modes but also paves the way for the systematic development of on-chip modulators based on active defects. National Research Foundation (NRF) Published version All the authors acknowledge the research funding support from the National Research Foundation (NRF) Singapore Grant No. NRF-CRP23-2019-0005 (TERACOMM). 2024-10-09T02:19:49Z 2024-10-09T02:19:49Z 2024 Journal Article Jayaram, S., Tan, Y. J., Navaratna, N., Tan, T. C., Chong, Y. & Singh, R. (2024). Valley-Hall photonic crystal waveguides under non-Hermitian active defect. Applied Physics Letters, 125(5), 051101-. https://dx.doi.org/10.1063/5.0213641 0003-6951 https://hdl.handle.net/10356/180487 10.1063/5.0213641 2-s2.0-85199861106 5 125 051101 en NRF-CRP23-2019-0005 (TERACOMM) Applied Physics Letters © 2024 Author(s). Published under an exclusive license by AIP Publishing. All rights reserved. This article may be downloaded for personal use only. Any other use requires prior permission of the copyright holder. The Version of Record is available online at http://doi.org/10.1063/5.0213641 application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Physics
Crystal waveguides
Hermitians
spellingShingle Physics
Crystal waveguides
Hermitians
Jayaram, Shrinivas
Tan, Yi Ji
Navaratna, Nikhil
Tan, Thomas CaiWei
Chong, Yidong
Singh, Ranjan
Valley-Hall photonic crystal waveguides under non-Hermitian active defect
description Photonic transport facilitated by topological protection is a proposed advantage of photonic topological waveguides based on valley photonic crystals (VPCs). Although topological protection significantly suppresses backscattering in these waveguides, it is often desirable to achieve active control over the transmission characteristics. We utilize photoexcited carriers in silicon to implement an active defect—a local, actively tunable, dissipative non-Hermitian perturbation in the path of a terahertz VPC waveguide—and systematically characterize the transport characteristics. We study waveguides constructed from different VPC interfaces (zigzag and bearded) and show that the high group index VPC waveguide modes are more strongly modulated by the phototunable defect. In both the waveguides, the faster modes exhibit approximately linear variation in transmission loss with increase in defect through enhanced photocarrier generation. However, for slower modes, the transmission loss varies nonlinearly, indicative of enhanced interaction with the active defect. We are able to model this behavior in terms of a group delay dependent loss. Our study not only highlights the superior performance of low index VPC waveguide modes but also paves the way for the systematic development of on-chip modulators based on active defects.
author2 School of Physical and Mathematical Sciences
author_facet School of Physical and Mathematical Sciences
Jayaram, Shrinivas
Tan, Yi Ji
Navaratna, Nikhil
Tan, Thomas CaiWei
Chong, Yidong
Singh, Ranjan
format Article
author Jayaram, Shrinivas
Tan, Yi Ji
Navaratna, Nikhil
Tan, Thomas CaiWei
Chong, Yidong
Singh, Ranjan
author_sort Jayaram, Shrinivas
title Valley-Hall photonic crystal waveguides under non-Hermitian active defect
title_short Valley-Hall photonic crystal waveguides under non-Hermitian active defect
title_full Valley-Hall photonic crystal waveguides under non-Hermitian active defect
title_fullStr Valley-Hall photonic crystal waveguides under non-Hermitian active defect
title_full_unstemmed Valley-Hall photonic crystal waveguides under non-Hermitian active defect
title_sort valley-hall photonic crystal waveguides under non-hermitian active defect
publishDate 2024
url https://hdl.handle.net/10356/180487
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