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Fei J, Zhang X, Zhang Q, Yang Y, Wang Z, Deng C, Huang Y, Wang T. Exceptional point enhanced nanoparticle detection in deformed Reuleaux-triangle microcavity. FRONTIERS OF OPTOELECTRONICS 2024; 17:27. [PMID: 39115622 PMCID: PMC11310378 DOI: 10.1007/s12200-024-00131-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 07/03/2024] [Indexed: 08/11/2024]
Abstract
In this paper, we propose a deformed Reuleaux-triangle resonator (RTR) to form exceptional point (EP) which results in the detection sensitivity enhancement of nanoparticle. After introducing single nanoparticle to the deformed RTR at EP, frequency splitting obtains an enhancement of more than 6 times compared with non-deformed RTR. In addition, EP induced a result that the far field pattern of chiral mode responses significantly to external perturbation, corresponding to the change in internal chirality. Therefore, single nanoparticle with far distance of more than 4000 nm can be detected by measuring the variation of far field directional emission. Compared to traditional frequency splitting, the far field pattern produced in deformed RTR provides a cost-effective and convenient path to detect single nanoparticle at a long distance, without using tunable laser and external coupler. Our structure indicates great potential in high sensitivity sensor and label-free detector.
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Affiliation(s)
- Jinhao Fei
- Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, School of Communication and Information Engineering, Shanghai University, Shanghai, 200444, China
| | - Xiaobei Zhang
- Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, School of Communication and Information Engineering, Shanghai University, Shanghai, 200444, China.
| | - Qi Zhang
- Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, School of Communication and Information Engineering, Shanghai University, Shanghai, 200444, China
| | - Yong Yang
- Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, School of Communication and Information Engineering, Shanghai University, Shanghai, 200444, China
| | - Zijie Wang
- Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, School of Communication and Information Engineering, Shanghai University, Shanghai, 200444, China
| | - Chuanlu Deng
- Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, School of Communication and Information Engineering, Shanghai University, Shanghai, 200444, China
| | - Yi Huang
- Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, School of Communication and Information Engineering, Shanghai University, Shanghai, 200444, China
| | - Tingyun Wang
- Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, School of Communication and Information Engineering, Shanghai University, Shanghai, 200444, China
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Kim H, Gwak S, Yu HH, Ryu J, Kim CM, Yi CH. Maximization of a frequency splitting on continuous exceptional points in asymmetric optical microdisks. OPTICS EXPRESS 2023; 31:12634-12644. [PMID: 37157419 DOI: 10.1364/oe.484812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We study a systematic formation of continuous exceptional points (EPs) in a fully-asymmetric optical microdisk. A parametric generation of chiral EP modes is investigated by analyzing asymmetricity-dependent coupling elements in an effective Hamiltonian. It is shown that given the external perturbation, the frequency splitting around EPs is scaled by the fundamental "strength" of EPs [J. Wiersig, Phys. Rev. Res.4, 023121 (2022)10.1103/PhysRevResearch.4.023121] multiplied by the extra responding strength of the newly added perturbation. Our finding demonstrates that the sensitivity of EP-based sensors can be maximized by carefully examining the continuous formation of EPs.
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Gwak S, Ryu J, Kim H, Yu HH, Kim CM, Yi CH. Far-Field Correlations Verifying Non-Hermitian Degeneracy of Optical Modes. PHYSICAL REVIEW LETTERS 2022; 129:074101. [PMID: 36018704 DOI: 10.1103/physrevlett.129.074101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
An experimental verification of an exceptional point (EP) in a stand-alone chaotic microcavity is a tough issue because as deformation parameters are fixed the traditional frequency analysis methods cannot be applied any more. Through numerical investigations with an asymmetric Reuleaux triangle microcavity (ARTM), we find that the eigenvalue difference of paired modes can approach near-zero regardless of nonorthogonality of the modes. In this case, for a definite verification of EPs in experiments, wave function coalescence should be confirmed. For this, we suggest the method of exploiting correlation of far-field patterns (FFPs), which is directly related to spatial mode patterns. In an ARTM, we demonstrate that the FFP correlation of paired modes can be used to confirm wave function coalescence when an eigenvalue difference approaches near zero.
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Affiliation(s)
- Sunjae Gwak
- Department of Physics and Chemistry, DGIST, Daegu 42988, Republic of Korea
| | - Jinhyeok Ryu
- Department of Physics and Chemistry, DGIST, Daegu 42988, Republic of Korea
| | - Hyundong Kim
- Department of Physics and Chemistry, DGIST, Daegu 42988, Republic of Korea
| | - Hyeon-Hye Yu
- Department of Physics and Chemistry, DGIST, Daegu 42988, Republic of Korea
| | - Chil-Min Kim
- Department of Physics and Chemistry, DGIST, Daegu 42988, Republic of Korea
| | - Chang-Hwan Yi
- Center for Theoretical Physics of Complex Systems, IBS, Daejeon 34126, Republic of Korea
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Park SJ, Kim I, Rim S, Choi M. Chiral exceptional point in transformation cavity. OPTICS LETTERS 2022; 47:1705-1708. [PMID: 35363713 DOI: 10.1364/ol.453792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 02/28/2022] [Indexed: 06/14/2023]
Abstract
Unlike the ideal circular whispering gallery cavities, those without mirror symmetry intrinsically support resonant modes exhibiting chirality which indicates an imbalance between clockwise and counterclockwise wave components. In extreme cases, nearly degenerate pairs of copropagating modes can be found around the chiral exceptional points (EPs) in parameter spaces. The chiral EPs have been studied in various schemes; however, most attention has been focused on the cases with piecewise constant or periodic refractive index profiles. In this Letter, we report the formation of a chiral EP in a gradient-index cavity designed by conformal transformation optics. Here, the mirror symmetry of the cavity is broken solely by its gradient index profile, and the parameter space is constructed with coordinate transformation parameters. We unveil the chirality, nonorthogonality, and complex-square-root topology near the chiral EP, which can be explained by the non-Hermitian model Hamiltonian.
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