Dynamically tuneable helicity in twisted electromagnetic resonators
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arXiv
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| Autori principali: | , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866918396609691648 |
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| author | Paterson, E. C. I. Bourhill, J. Tobar, M. E. Goryachev, M. |
| author_facet | Paterson, E. C. I. Bourhill, J. Tobar, M. E. Goryachev, M. |
| contents | We report the generation of helical electromagnetic radiation in a microwave cavity resonator, achieved by introducing mirror asymmetry, i.e., chirality, through a controlled geometric twist of the conducting boundary conditions. The emergence of electromagnetic helicity is attributed to a nonzero spatial overlap between the electric and magnetic mode eigenvectors, quantified by $\text{Im}\left[\vec{\mathbf{E}}_i(\vec{r})\cdot{\vec{\mathbf{H}}}_i^*(\vec{r})\right]$, a feature not observed in conventional cavity resonators. This phenomenon originates from magnetoelectric coupling between nearly degenerate transverse electric (TE) and transverse magnetic (TM) modes, resulting in a measurable frequency shift of the resonant modes as a function of the twist angle, $ϕ$. In addition to the bulk helicity induced by global geometric twist, internal helical corrugations break structural symmetry on the surface, introducing an effective surface chirality $κ_{\text{eff}}$, which perturbs the resonant conditions and contributes to asymmetric frequency tuning. By dynamically varying $ϕ$, we demonstrate real-time, macroscopic manipulation of both electromagnetic helicity and resonant frequency. Furthermore, we investigate the underlying mode-coupling dynamics of the system, highlighting strong photon-photon interactions. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2510_01217 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Dynamically tuneable helicity in twisted electromagnetic resonators Paterson, E. C. I. Bourhill, J. Tobar, M. E. Goryachev, M. Optics We report the generation of helical electromagnetic radiation in a microwave cavity resonator, achieved by introducing mirror asymmetry, i.e., chirality, through a controlled geometric twist of the conducting boundary conditions. The emergence of electromagnetic helicity is attributed to a nonzero spatial overlap between the electric and magnetic mode eigenvectors, quantified by $\text{Im}\left[\vec{\mathbf{E}}_i(\vec{r})\cdot{\vec{\mathbf{H}}}_i^*(\vec{r})\right]$, a feature not observed in conventional cavity resonators. This phenomenon originates from magnetoelectric coupling between nearly degenerate transverse electric (TE) and transverse magnetic (TM) modes, resulting in a measurable frequency shift of the resonant modes as a function of the twist angle, $ϕ$. In addition to the bulk helicity induced by global geometric twist, internal helical corrugations break structural symmetry on the surface, introducing an effective surface chirality $κ_{\text{eff}}$, which perturbs the resonant conditions and contributes to asymmetric frequency tuning. By dynamically varying $ϕ$, we demonstrate real-time, macroscopic manipulation of both electromagnetic helicity and resonant frequency. Furthermore, we investigate the underlying mode-coupling dynamics of the system, highlighting strong photon-photon interactions. |
| title | Dynamically tuneable helicity in twisted electromagnetic resonators |
| topic | Optics |
| url | https://arxiv.org/abs/2510.01217 |