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| Main Authors: | , , , , , , , , , |
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| Format: | Preprint |
| Published: |
2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2605.21432 |
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| _version_ | 1866918514746458112 |
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| author | Harwood, Anthony C Lim, Sean Z J Raziman, T V Li, Yan Stones, Joseph Tisch, John W G Horsley, Simon A R Vezzoli, Stefano Pendry, John B Sapienza, Riccardo |
| author_facet | Harwood, Anthony C Lim, Sean Z J Raziman, T V Li, Yan Stones, Joseph Tisch, John W G Horsley, Simon A R Vezzoli, Stefano Pendry, John B Sapienza, Riccardo |
| contents | Transparent conducting oxides near their epsilon-near-zero frequency exhibit near-unity ultrafast modulations of the refractive index which have enabled the field of time-varying metamaterials, yet the underlying carrier dynamics at high driving fluences remain poorly understood. Here, we report ultrafast modulations in the reflectivity and transmissivity of indium tin oxide, and a non-monotonic oscillatory behavior. This is especially evident in the time evolution of the complex Fresnel coefficients retrieved directly from pump-probe spectrograms using a optical gating technique, GRUMPY FROG. The dynamics of the retrieved plasma frequency and damping coefficient are well captured by an extended two-temperature model incorporating a competing nonlinear interband process: at high fluences, Auger-type scattering of hot conduction electrons promotes valence band carriers, increasing the plasma frequency while accelerating hot-electron cooling and raising the damping coefficient. These results clarify the origin of anomalous high-fluence dynamics in indium tin oxide and identify a fluence-tuneable modulation dynamic with direct implications for ultrafast refractive index engineering in time-varying photonic devices and optical switching |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_21432 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Intraband and Interband Competition Drives Ultrafast Modulations of Indium Tin Oxide Harwood, Anthony C Lim, Sean Z J Raziman, T V Li, Yan Stones, Joseph Tisch, John W G Horsley, Simon A R Vezzoli, Stefano Pendry, John B Sapienza, Riccardo Optics Transparent conducting oxides near their epsilon-near-zero frequency exhibit near-unity ultrafast modulations of the refractive index which have enabled the field of time-varying metamaterials, yet the underlying carrier dynamics at high driving fluences remain poorly understood. Here, we report ultrafast modulations in the reflectivity and transmissivity of indium tin oxide, and a non-monotonic oscillatory behavior. This is especially evident in the time evolution of the complex Fresnel coefficients retrieved directly from pump-probe spectrograms using a optical gating technique, GRUMPY FROG. The dynamics of the retrieved plasma frequency and damping coefficient are well captured by an extended two-temperature model incorporating a competing nonlinear interband process: at high fluences, Auger-type scattering of hot conduction electrons promotes valence band carriers, increasing the plasma frequency while accelerating hot-electron cooling and raising the damping coefficient. These results clarify the origin of anomalous high-fluence dynamics in indium tin oxide and identify a fluence-tuneable modulation dynamic with direct implications for ultrafast refractive index engineering in time-varying photonic devices and optical switching |
| title | Intraband and Interband Competition Drives Ultrafast Modulations of Indium Tin Oxide |
| topic | Optics |
| url | https://arxiv.org/abs/2605.21432 |