(167a) Design and Optimization of a Tunable Ag-Wire Based Plasmonic Perfect Absorber

A plasmonic perfect absorber is a material that has been structurally designed to achieve perfect optical absorption. Plasmonic perfect absorbers have increasingly attracted attention in the field of photonics in the last decade due to their capacity of absorbing and enhancing electromagnetic (EM) waves to the nanometer scale. Usually, perfect absorbers are composed of periodically arranged resonant metallic nanostructures by stacking metal-dielectric-metal layers sequentially in a sandwiched arrangement. Their resonant absorption wavelength is controlled by changing their design parameters, such as the shape, size, layer thickness, structural period, and composition of the plasmonic structure. Due to their interesting optical properties, perfect absorbers have potential applications in different fields, such as resonators, refractive index (RI) sensing, nanoantennas, surface enhanced Raman scattering, plasmonic solar cells, biosensing and other optical and optoelectronic fields.

In the present work we demonstrate the computational design and experimental fabrication of a tunable plasmonic perfect absorber in the near infrared (NIR) and infrared (IR) regime of the electromagnetic spectrum. The proposed plasmonic absorber design is made of an array of a metal-dielectric-metal structure consisting of a silica layer sandwiched between a periodic silver nanowire array and a silver mirror layer. We analyze the impact of the structural and geometric properties of the designed absorber, such as the metal and dielectric layer thickness, absorber duty cycle, and the periodicity of the silver nanowire array to determine the optimal absorption parameters. Employing the optimized simulation, we have fabricated and confirmed the absorption/reflectance results experimentally using Fourier-transform infrared spectroscopy. Due to the very high observed absorption sensitivity, we anticipate that this plasmonic structure could serve as a sensitive and versatile platform in refractive index detection and near infrared process monitoring.