Broadband multi-resonant circular dichroism in metal-VO2 hybrid dagger-like plasmonic structure for switching application

Metallic and metal-VO2 hybrid dagger-like novel chiral plasmonic structure is proposed and demonstrated numerically using finite difference time domain (FDTD) computation to realize broadband multi-resonant circular dichroism (CD). CD switching is realized in the hybrid system that can be actively controlled externally. Dagger-like structure is considered where asymmetry is introduced in both the arms of a dagger structure to break in-plane rotational symmetry making the structure in-planar chiral. Multi-resonant broadband CD between visible to infrared frequencies is observed in pure asymmetric metallic dagger-like structure (MDLS) made of gold, as well as, in asymmetric metal-VO2 hybrid dagger-like structure (MVHDLS). Interestingly, multi-resonant CD in MVHDLS vanishes completely when VO2 phase changes from semiconducting to metallic phase. Dynamic control of VO2 phase externally enables us to realize CD switching action in MVHDLS. The proposed structure opens up the possibility of switching based plasmonic and photonic CD applications.