Ultrafast Topological Transitions Driven by Permittivity Modulation in Non-Hermitian Multilayers
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866917070701068288 |
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| author | Simone, Giuseppina |
| author_facet | Simone, Giuseppina |
| contents | Ultrafast permittivity modulation in epsilon-near-zero (ENZ) media provides a pathway for real-time control of non-Hermitian photonic topology. We model ultrafast topological dynamics in an ITO/SiO$_2$/Ag multilayer supporting hybrid epsilon-near-zero (ENZ)-plasmon modes. Using a time-dependent Drude-Lorentz permittivity for ITO and rigorous coupled-wave analysis, it is found that carrier relaxation with a 10-ps time constant redshifts the ENZ resonance from 490 to 525~nm and shifts the reflection-phase singularities across the angle--wavelength plane. The motion of these singularities corresponds to the displacement of exceptional points and a discrete change in the cumulative winding number. The transient Floquet-like band structure exhibits avoided crossings and Dirac-type dispersions driven by ENZ modulation. The results directly link picosecond-scale permittivity dynamics to quantized topological transitions in non-Hermitian photonic systems. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_06963 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Ultrafast Topological Transitions Driven by Permittivity Modulation in Non-Hermitian Multilayers Simone, Giuseppina Optics Ultrafast permittivity modulation in epsilon-near-zero (ENZ) media provides a pathway for real-time control of non-Hermitian photonic topology. We model ultrafast topological dynamics in an ITO/SiO$_2$/Ag multilayer supporting hybrid epsilon-near-zero (ENZ)-plasmon modes. Using a time-dependent Drude-Lorentz permittivity for ITO and rigorous coupled-wave analysis, it is found that carrier relaxation with a 10-ps time constant redshifts the ENZ resonance from 490 to 525~nm and shifts the reflection-phase singularities across the angle--wavelength plane. The motion of these singularities corresponds to the displacement of exceptional points and a discrete change in the cumulative winding number. The transient Floquet-like band structure exhibits avoided crossings and Dirac-type dispersions driven by ENZ modulation. The results directly link picosecond-scale permittivity dynamics to quantized topological transitions in non-Hermitian photonic systems. |
| title | Ultrafast Topological Transitions Driven by Permittivity Modulation in Non-Hermitian Multilayers |
| topic | Optics |
| url | https://arxiv.org/abs/2511.06963 |