Fabrication of THz metalens by ultraviolet femtosecond laser ablation

Y. Hakamada; M. Matoba; H. Sakurai; K. Konishi

doi:10.1117/12.3002130

11 March 2024 Fabrication of THz metalens by ultraviolet femtosecond laser ablation

Y. Hakamada, M. Matoba, H. Sakurai, K. Konishi

Proceedings Volume 12885, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XVII; 128850R (2024) https://doi.org/10.1117/12.3002130
Event: SPIE OPTO, 2024, San Francisco, California, United States

Abstract

Planar metamaterials, or metasurfaces, have recently gained attention to realize ultra-thin, functional optical components. Metalenses, or metasurfaces with light-focusing capabilities, have gained attention to greatly reduce the size of conventional optics, including in the terahertz regime. The fabrication of metalenses currently relies on lithography techniques utilized in a clean room environment, and a simpler fabrication method is needed for more extensive use of metalenses. In this study, we report the fabrication of a THz metalens by using femtosecond laser ablation in a standard laboratory environment. The metalens, targeted at 0.8 THz, was fabricated by drilling through-holes with a 343-nm ultraviolet femtosecond laser on a 75-μm-thick high-resistivity silicon substrate. We evaluate the performance of the fabricated metalens with a THz imaging setup, and measure a focused spot full width at half maximum (FWHM) of 0.9 mm and a focusing efficiency of 67.8% when compared to a commercially available lens, results comparable to lithography fabricated metalenses. These results demonstrate the feasibility of the combination of laser processing with metasurface fabrication for the THz region, and represent a new, more versatile alternative to lithography for THz metalens fabrication.

Conference Presentation

Citation Download Citation

Y. Hakamada, M. Matoba, H. Sakurai, and K. Konishi "Fabrication of THz metalens by ultraviolet femtosecond laser ablation", Proc. SPIE 12885, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XVII, 128850R (11 March 2024); https://doi.org/10.1117/12.3002130

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