Dielectric dual-dimer metasurface for enhanced mid-infrared chiral sensing under both excitation modes

Abstract Chirality ( C ) is a fundamental symmetry property of objects. Detecting and distinguishing molecular chirality in the infrared spectrum important life sciences, biology, chemistry. In this paper, we demonstrate an achiral metasurface based on gaped dual-germanium-dimer array for enhanced mid-infrared chiral sensing under both circularly polarized light (CPL) linearly (LPL) excitations. With metasurface, strong electric magnetic dipole resonances with large field enhancement can be generated, resulting accessible superchiral hotspot dimer gaps excitation modes. The maximum enhancements exceed 220 100 bare 70 60 coated 50 nm biolayer excitations, respectively. Importantly, high volume-averaged E_ave 241 (444) E_ave_bio 161 (102) CPL achieved it biolayer, These results may open up new possibilities ultrasensitive vibrational circular dichroism (VCD) rotational optical dispersion (ORD) spectroscopy range.