Study on circular dichroism of chiral helical carbon coils in microwave range

Helical carbon coils (HCCs), characterized by their unique chiral structures and exceptional physical properties, have emerged as a frontier research focus stemming from their distinctive electromagnetic wave interaction mechanisms. However, systematic investigations into the circular dichroism (CD) of HCCs remain notably absent in current research. In this work, a comprehensive simulation framework was established to characterize the CD of HCC arrays across the microwave range (2–18 GHz). The impacts of geometric parameters of HCCs, such as the coil diameter, pitch, wire diameter, and coil array period, on the CD have been studied. The simulation results indicate that the increase in the pitch is the optimal adjustment strategy for CD enhancement. In addition, the CD exhibits a non-monotonic dependence on coil length. Most importantly, with the decrease in coil size, the CD diminishes progressively and disappears completely when the coil diameter is reduced to 10.7 μm. This research provides a guideline for designing chiral HCCs with CD in the microwave range.