Enhancement and sensing applications of ultra-narrow band circular dichroism of the chiral nanopore films based on Bragg reflector

Abstract

Narrow-band circular dichroism (CD) has attracted considerable attention in the high-sensitivity detection of chiral molecules and chiral catalysis. However, achieving dynamic adjustment of narrow-band CD signals is challenging. In this study, we introduce a disruption layer (DL) and molybdenum disulfide (MoS₂) into an L-shaped chiral nanohole array based on a distributed Bragg reflector (DBR), forming L-shaped chiral nanoholes (LCNAs/DL-DBR/MoS₂), and investigate the mechanism of CD signal generation. Simulation results show that LCNAs/DL-DBR/MoS₂ generate three narrow-band CD signals in the visible region. Analysis of the near-field electric field maps reveals that the three CD peaks of LCNAs/DL-DBR/MoS₂ are caused by three Tamm resonances in the DBR layer. The producing and adjusting mechanisms of the CD signals are achieved by changing the structural parameters and the number of MoS₂ layers. Dynamic adjustment of the CD signals of LCNAs/DL-DBR/MoS₂ can be achieved by changing the environmental temperature. Furthermore, by altering the refractive index of the environment and the DBR layer, it is demonstrated that LCNAs/DL-DBR/MoS₂ has a high-quality factor. Our theoretical simulations aid in the design of UNB chiral devices, opening up new avenues for environmental monitoring and the detection of chiral molecules with exceptional sensitivity.