Ultra-broad bandgap metal-insulator-metal waveguide filter with symmetrical stubs and defects

Highlights

• An ultrawide bandgap plasmonic-based filter consisting of defects and stubs is designed and investigated for the first time.

• A tunable and wide bandgap about 1.35 times compared to its counterpart without nanorod defects is acquired.

• It is found that the nanorod defects and the number of periods play crucial roles to affect bandgap performance.

• The proposed plasmonic waveguide filter may have meaningful applications in ultra-fine spectrum analysis and high-density nanoplasmonic integration circuits.

Abstract

An ultra-broad bandgap plasmonic based filter that consists of a metal-insulator-metal waveguide with symmetrical stubs and defects is designed and investigated for the first time. A tunable wide bandgap can be achieved by introducing the defects into the stubs and a larger bandgap width about 1.35 times compared to its counterpart without defects is acquired. It is found that both the defects and number of periods play the crucial roles to affect the bandgap performance, which is attributed to the change of effective refractive index and plasmon resonance modes in the proposed structure. The proposed plasmonic filter has potential to be a promising alternative structure to realize in integrated optical circuits for optical trapping and tunable devices.