Anti-reflection coating design for metallic terahertz meta-materials
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arXiv
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| Format: | Preprint |
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2017
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| author | Pancaldi, M. Freeman, R. Hudl, M. Hoffmann, M. C. Urazhdin, S. Vavassori, P. Bonetti, S. |
| author_facet | Pancaldi, M. Freeman, R. Hudl, M. Hoffmann, M. C. Urazhdin, S. Vavassori, P. Bonetti, S. |
| contents | We demonstrate a silicon-based, single-layer anti-reflection coating that suppresses the reflectivity of metals at near-infrared frequencies, enabling optical probing of nano-scale structures embedded in highly reflective surroundings. Our design does not affect the interaction of terahertz radiation with metallic structures that can be used to achieve terahertz near-field enhancement. We have verified the functionality of the design by calculating and measuring the reflectivity of both infrared and terahertz radiation from a silicon/gold double layer as a function of the silicon thickness. We have also fabricated the unit cell of a terahertz meta-material, a dipole antenna comprising two 20-nm thick extended gold plates separated by a 2 $μ$m gap, where the terahertz field is locally enhanced. We used the time-domain finite element method to demonstrate that such near-field enhancement is preserved in the presence of the anti-reflection coating. Finally, we performed magneto-optical Kerr effect measurements on a single 3-nm thick, 1-$μ$m wide magnetic wire placed in the gap of such a dipole antenna. The wire only occupies 2\% of the area probed by the laser beam, but its magneto-optical response can be clearly detected. Our design paves the way for ultrafast time-resolved studies, using table-top femtosecond near-infrared lasers, of dynamics in nano-structures driven by strong terahertz radiation. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_1711_05670 |
| institution | arXiv |
| publishDate | 2017 |
| record_format | arxiv |
| spellingShingle | Anti-reflection coating design for metallic terahertz meta-materials Pancaldi, M. Freeman, R. Hudl, M. Hoffmann, M. C. Urazhdin, S. Vavassori, P. Bonetti, S. Applied Physics Other Condensed Matter We demonstrate a silicon-based, single-layer anti-reflection coating that suppresses the reflectivity of metals at near-infrared frequencies, enabling optical probing of nano-scale structures embedded in highly reflective surroundings. Our design does not affect the interaction of terahertz radiation with metallic structures that can be used to achieve terahertz near-field enhancement. We have verified the functionality of the design by calculating and measuring the reflectivity of both infrared and terahertz radiation from a silicon/gold double layer as a function of the silicon thickness. We have also fabricated the unit cell of a terahertz meta-material, a dipole antenna comprising two 20-nm thick extended gold plates separated by a 2 $μ$m gap, where the terahertz field is locally enhanced. We used the time-domain finite element method to demonstrate that such near-field enhancement is preserved in the presence of the anti-reflection coating. Finally, we performed magneto-optical Kerr effect measurements on a single 3-nm thick, 1-$μ$m wide magnetic wire placed in the gap of such a dipole antenna. The wire only occupies 2\% of the area probed by the laser beam, but its magneto-optical response can be clearly detected. Our design paves the way for ultrafast time-resolved studies, using table-top femtosecond near-infrared lasers, of dynamics in nano-structures driven by strong terahertz radiation. |
| title | Anti-reflection coating design for metallic terahertz meta-materials |
| topic | Applied Physics Other Condensed Matter |
| url | https://arxiv.org/abs/1711.05670 |