Giant enhancement of nonreciprocity in gyrotropic heterostructures

Journal Article · Mon Dec 11 00:00:00 EST 2023 · Scientific Reports

DOI:https://doi.org/10.1038/s41598-023-48503-9· OSTI ID:2229484

Katsantonis, Ioannis; Tasolamprou, Anna C.; Koschny, Thomas; Economou, Eleftherios N.; Kafesaki, Maria; Valagiannopoulos, Constantinos

Abstract Nonreciprocity is a highly desirable feature in photonic media since it allows for control over the traveling electromagnetic waves, in a way that goes far beyond ordinary filtering. One of the most conventional ways to achieve nonreciprocity is via employing gyrotropic materials; however, their time-reversal-symmetry-breaking effects are very weak and, hence, large, bulky setups combined with very strong magnetic biases are required for technologically useful devices. In this work, artificial heterostructures are introduced to enhance the effective nonreciprocal behavior by reducing the contribution of the diagonal susceptibilities in the collective response; in this way, the off-diagonal ones, that are responsible for nonreciprocity, seem bigger. In particular, alternating gyrotropic and metallic or plasmonic films make an epsilon-near-zero (ENZ) effective-medium by averaging the diagonal permittivities of opposite sign, representing the consecutive layers. The homogenization process leaves unaltered the nonzero off-diagonal permittivities of the original gyrotropic substance, which become dominant and ignite strong nonreciprocal response. Realistic material examples that could be implemented experimentally in the mid-infrared spectrum are provided while the robustness of the enhanced nonreciprocity in the presence of actual media losses is discussed and bandwidth limitations due to the unavoidable frequency dispersion are elaborated. The proposed concept can be extensively utilized in designing optical devices that serve a wide range of applications from signal isolation and wave circulation to unidirectional propagation and asymmetric power amplification.

• Research Organization: Ames Laboratory (AMES), Ames, IA (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
• Grant/Contract Number: AC02-07CH11358
• OSTI ID: 2229484
• Alternate ID(s): OSTI ID: 2234282
• Report Number(s): IS-J-11,217; 21986; PII: 48503
• Journal Information: Scientific Reports, Journal Name: Scientific Reports Vol. 13 Journal Issue: 1; ISSN 2045-2322
• Publisher: Nature Publishing Group
• Country of Publication: United Kingdom
• Language: English

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