Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Applied Physics | en_US |
| dc.contributor.advisor | Yu, Siu Fung (AP) | en_US |
| dc.contributor.advisor | Fung, Kin-hung (AP) | en_US |
| dc.creator | Jiang, Yimin | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/14160 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | en_US |
| dc.rights | All rights reserved | en_US |
| dc.title | Theoretical study of topological singularities in nonreciprocal non-hermitian metasurface | en_US |
| dcterms.abstract | Since the first experimental realization of photonic topological insulator using nonreciprocal gyromagnets in 2008, optical control systems have emerged as a widely-used platform for topological physics in both theoretical and experimental studies, where gyromagnets are implemented as the origin of nonreciprocity supporting photonic chiral edge states. As the topological classification of Hermitian systems becomes mature, the research focus shifts to non-Hermitian topology, where the system has more degrees of freedom, thus the classification becomes more intricate. Due to the ease of implementing non-Hermiticity via optical gain and loss, optical system has become a key platform for non-Hermitian topology in contrast to quantum system. | en_US |
| dcterms.abstract | Therefore, this project aims at the analytical study of topological properties of a 1D-periodic non-Hermitian nonreciprocal electromagnetic metasurface, which is composed of cylinder arrays of gyromagnetic yttrium iron garnet (YIG) and lossy dielectric materials. Using Mie theory and multiple scattering theory, the rigorous solution of the scattered field under plane wave incidence is obtained, enabling a physical interpretation of the intrinsic mechanism. | en_US |
| dcterms.abstract | The nontrivial topology is identified in the nonreciprocal transmission, characterized by robust polarization singularities in the parameter spaces. The singularities arise from the coupling between the YIG array and the dielectric array; and their robustness is shown to be protected by the strong nonreciprocal magnetic response of the YIG array. The results demonstrate the interplay of nonreciprocity and non-Hermiticity in a topological optical system – as the coupling effect on lossy dielectric array is nonreciprocal, the excitations on the absorption loss are different under opposite incident directions, resulting in the nonreciprocal transmission. The mechanism of robustness induced by nonreciprocal magnets can be generalized to other systems and may offer insights into the implementation of non-Hermitian topological classifications. The results may also inspire the design of optical isolators and polarization modulators, through zero transmission at singularities and associated vortex polarization fields. | en_US |
| dcterms.extent | 1 volume (unpaged) : color illustrations | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2025 | en_US |
| dcterms.educationalLevel | M.Phil. | en_US |
| dcterms.educationalLevel | All Master | en_US |
| dcterms.accessRights | open access | en_US |
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