Ultra-narrowband Emitters/Absorbers Based on Metal-Insulator-Metal Stacks for Nondispersive Infrared Gas Sensors

Native narrowband emitters/absorbers in the mid-infrared range are highly demanded in nondispersive infrared (NDIR) gas sensors, which not only decrease the complexity of the whole system, but also improve their performance. Metamaterials with narrowband features are considered as high-potential candidate materials for NDIR gas sensors because of their low cost, small volume, and almost arbitrary working band. Recently, narrowband emitters based on metamaterials have been proposed and proved to be feasible; however, the inherent losses in metals limit the ability to achieve ultra-narrowband emitters/absorbers. In order to break through this inherent defect in metamaterials and realize high-performance NDIR gas sensors, surface lattice resonance (SLR) based on parallel coupling between the localized surface plasmon resonance (LSRR) and the lattice diffraction in metamaterials has been obtained both in the simulation and experiment in this work. In the results, the bandwidth of the SLR in the mid-infrared range is an order of magnitude lower than traditional LSRR; besides, the strength of SLR can be modulated by the insulator expediently. The results may fuel the launch of this delocalized parallel coupling to practical applications for realizing ultra-narrowband resonance for high-performance NDIR gas sensors.