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Using phase-change materials to switch the direction of reflectionless light propagation in non-PT-symmetric structures

Veronis, Georgios and Huang, Yin and Shen, Yuecheng and Min, Changjun (2018) Using phase-change materials to switch the direction of reflectionless light propagation in non-PT-symmetric structures. In: Active Photonic Platforms X. Proceedings of SPIE. No.10721. Society of Photo-Optical Instrumentation Engineers , Bellingham, WA, Art. No. 107210I. ISBN 9781510620131. http://resolver.caltech.edu/CaltechAUTHORS:20181212-155248801

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Abstract

We introduce a non-parity-time-symmetric three-layer structure, consisting of a gain medium layer sandwiched between two phase-change medium layers for switching of the direction of reflectionless light propagation. We show that for this structure unidirectional reflectionlessness in the forward direction can be switched to unidirectional reflectionlessness in the backward direction at the optical communication wavelength by switching the phase-change material Ge2Sb2Te5 (GST) from its amorphous to its crystalline phase. We also show that it is the existence of exceptional points for this structure with GST in both its amorphous and crystalline phases which leads to unidirectional reflectionless propagation in the forward direction for GST in its amorphous phase, and in the backward direction for GST in its crystalline phase. Our results could be potentially important for developing a new generation of compact active free-space optical devices. We also show that phase-change materials can be used to switch photonic nanostructures between cloaking and superscattering regimes at mid-infrared wavelengths. More specifically, we investigate the scattering properties of subwavelength three-layer cylindrical structures in which the material in the outer shell is the phase-change material GST. We first show that, when GST is switched between its amorphous and crystalline phases, properly designed electrically small structures can switch between resonant scattering and cloaking invisibility regimes. The contrast ratio between the scattering cross sections of the cloaking invisibility and resonant scattering regimes reaches almost unity. We then also show that larger, moderately small cylindrical structures can be designed to switch between superscattering and cloaking invisibility regimes, when GST is switched between its crystalline and amorphous phases. The contrast ratio between the scattering cross sections of cloaking invisibility and superscattering regimes can be as high as ~ 93%. Our results could be potentially important for developing a new generation of compact reconfigurable optical devices.


Item Type:Book Section
Related URLs:
URLURL TypeDescription
https://doi.org/10.1117/12.2322004DOIArticle
ORCID:
AuthorORCID
Shen, Yuecheng0000-0003-1990-8142
Additional Information:© 2018 Society of Photo-Optical Instrumentation Engineers. Georgios Veronis acknowledges support from the National Science Foundation under award no. 1254934.
Funders:
Funding AgencyGrant Number
NSFECCS-1254934
Subject Keywords:Physical optics; Nanophotonics and photonic crystals; Guided waves; Physical optics; Scattering, invisibility; Subwavelength structures
Record Number:CaltechAUTHORS:20181212-155248801
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20181212-155248801
Official Citation:Georgios Veronis, Yin Huang, Yuecheng Shen, Changjun Min, "Using phase-change materials to switch the direction of reflectionless light propagation in non-PT-symmetric structures", Proc. SPIE 10721, Active Photonic Platforms X, 107210I (19 September 2018); doi: 10.1117/12.2322004; https://doi.org/10.1117/12.2322004
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91745
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:13 Dec 2018 17:58
Last Modified:13 Dec 2018 17:58

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