Dielectric High‑Q Metasurfaces for Surface-Enhanced Deep-UV Absorption and Chiral Photonics

Deep ultraviolet (DUV) light is critical for novel developments in molecular spectroscopy, clinical imaging, and nanolithography. It is promising to advance these technologies by leveraging dielectric metasurfaces’ strong light manipulation capability. Realizing metasurfaces with high-quality-factor (high-Q) resonance in the DUV will be beneficial to those applications as they provide strong field enhancement and light confinement. However, due to the lack of high-index and low loss materials in this regime, it is considerably challenging to realize novel high-Q metasurfaces for sensing and light manipulation. We propose two device schemes wherein metasurfaces are strategically placed atop dielectric pillars or freestanding membranes. These configurations overcome the limitations associated with the low index contrast between the metasurfaces and substrates, thereby enabling the realization of high-Q resonance. We present multiple high-Q metasurfaces showcasing diverse DUV functionalities. The first application is spectrometerless biomolecular sensing. It is achieved through an array of high-Q metasurfaces exhibiting resonance associated with a quasi-bound state in the continuum (quasi-BIC). The strong field enhancement of the metasurfaces empowers the surface-enhanced deep-ultraviolet absorption (SEDUVA) of the biomolecules, thus allowing the detection of nanometer-thick analytes. Additionally, we introduce a nonlocal high-Q metasurface designed for DUV chiral photonics. It shows a narrow and near-unity peak in its DUV circular dichroism (CD) spectrum. These results establish a robust platform for developing novel nanophotonic devices and systems in the critical DUV wavelength range.