Near-zero-index behavior in indium antimonide revealed by phase-corrected terahertz reflection spectroscopy
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arXiv
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| Hauptverfasser: | , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866910766836219904 |
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| author | Jatkar, Kasturie D. Yeh, Tien-Tien Pancaldi, Matteo Bonetti, Stefano |
| author_facet | Jatkar, Kasturie D. Yeh, Tien-Tien Pancaldi, Matteo Bonetti, Stefano |
| contents | We developed a phase correction method for broadband terahertz time-domain spectroscopy in reflection geometry, which allows us to obtain quantitative and accurate values for the complex refractive index of materials. The process is analytical, based on the Kramers-Kronig relations, and does not require any computationally intensive algorithms. We validate it by extracting the refractive index of silicon, obtaining the nominal value with an accuracy better than 2.5\% over the 0.25--3.5 THz range, and better than 0.6\% in the 1--2 THz range. We use the method to experimentally observe that an undoped InSb crystal shows a refractive index of $n<1$ between 1 and 2 THz, in proximity to the plasma frequency of the material where, the amplitude of the group velocity goes as low as 0.08$c$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2412_21073 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Near-zero-index behavior in indium antimonide revealed by phase-corrected terahertz reflection spectroscopy Jatkar, Kasturie D. Yeh, Tien-Tien Pancaldi, Matteo Bonetti, Stefano Optics Applied Physics We developed a phase correction method for broadband terahertz time-domain spectroscopy in reflection geometry, which allows us to obtain quantitative and accurate values for the complex refractive index of materials. The process is analytical, based on the Kramers-Kronig relations, and does not require any computationally intensive algorithms. We validate it by extracting the refractive index of silicon, obtaining the nominal value with an accuracy better than 2.5\% over the 0.25--3.5 THz range, and better than 0.6\% in the 1--2 THz range. We use the method to experimentally observe that an undoped InSb crystal shows a refractive index of $n<1$ between 1 and 2 THz, in proximity to the plasma frequency of the material where, the amplitude of the group velocity goes as low as 0.08$c$. |
| title | Near-zero-index behavior in indium antimonide revealed by phase-corrected terahertz reflection spectroscopy |
| topic | Optics Applied Physics |
| url | https://arxiv.org/abs/2412.21073 |