Metamaterial-Enhanced Vibrational Circular Dichroism for Mid-Infrared Spectroscopic Nanosensors

Vibrational circular dichroism (VCD) spectroscopy plays an important role in molecule sensing. However, the main limitation is the weak molecule signals (~10
^-5
). In this work, we propose mid-infrared chiral metamaterials (MIRCMs) to demonstrate an enhanced VCD platform. Guided by temporal coupled-mode theory, our proposed chiral metamaterials break both the in-plane and the out-of-plane symmetry to create a larger circular dichroism signal. Leveraging such a platform, we demonstrated a 6-magnitude enhancement compared with traditional VCD spectroscopy. Moreover, we for the first time demonstrate the enhanced selective sensing of chiral mixtures, expanding the VCD spectroscopy for stereochemistry and clinical diagnosis applications.