Dual-band circular dichroism of titanium nitride chiral metamaterials by finite element method simulations

Titanium nitride (TiN) has been taken as a promising alternative to traditional noble metal materials, which exhibits excellent thermal stability and supports surface plasmon resonances. In this study, we present a novel chiral metamaterial based on TiN, comprising two rectangular TiN elements arranged periodically on a glass substrate. The geometry was optimized using finite element method (FEM) simulations to achieve significant dual-band circular dichroism (CD) at ∼1.76 µm and ∼2.25 µm. Under the optimized geometrical parameters and NIR incidence, the structure was revealed to exhibit maximum electric field enhancement and g - factor ∼5 and 9 times higher than that of experimental reports of TiN nanohelices. The underlying chiral optical response mechanisms were elucidated through analysis of the corresponding electric field, super chiral field, and charge density distributions along with multipolar resonances. This work suggests potential avenues for future design and application of plasmon chiral devices.