Si Metasurface for DUV Polariton-Enhanced Molecular Spectroscopy

Bo-Ray Lee¹, Mao Feng Chiang¹, Kuan-Heng Chen¹, Jia Hua Lee¹, Yu-Chuan Lin², Bor-Ran Li³, Yuri Kivshar⁴, Ming-Lun Tseng^1*

¹Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
²Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
³Institute of Biomedical Engineering, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
⁴Nonlinear Physics Centre, Australian National University, Canberra, Australia

* Presenter:Ming-Lun Tseng, email:mltseng@nycu.edu.tw

Deep ultraviolet (DUV) light plays a critical role in advancing biomedical spectroscopy and clinical applications. Metasurfaces, known for their ability to manipulate light at the nanoscale, present promising opportunities for enhancing DUV technologies. In this study, we investigate silicon (Si) as a candidate material for DUV nanophotonics and metasurfaces. Under DUV illumination, Si undergoes strong interband transitions, causing its dielectric constants to shift from positive to negative, enabling polaritonic resonances in its nanostructures. We introduce an innovative metasurface design based on an array of void unit cells that exhibit Kerker-type resonances near 266 nm. By adjusting the unit cell's tail angle, we fine-tuned the metasurface's field enhancement, achieving up to a 700-fold increase at 266 nm. This void metasurface was fabricated on Si chips, and its performance was validated through micro-spectrometer measurements, which aligned well with simulations. To explore biomedical potential, we tested the metasurface’s stability in various bioassay solvents, confirming its robustness. Furthermore, it enhances the autofluorescence of biomolecules and the double resonance Raman scattering of two-dimensional semiconductor materials. These results demonstrate a new class of plasmonic metasurfaces for the DUV spectrum, representing a significant step forward in DUV photonics and sensing technologies.

Keywords: Polaritonics, DUV, Biosensing