An ultra-broadband selective absorber has been realized with a hierarchical structure through integrating vacuum impedance-matched structure, quarter wavelength structure, and gradient refractive index structure. Through optimizing the design parameters of the proposed hierarchical structure, an ultra-broadband infrared absorber covering the three major atmospheric windows (0.7–2.5, 3–5, and 8–...

One varactor-tunable High Impedance Surface (HIS) is proposed and used in design of an active metamaterial absorber. The proposed HIS structure is based on mushroom-type HIS, in which varactors are introduced to adjust the effective capacitance and tune the resonance frequency. The primary ground plane is etched as the bias network for these loaded varactors, and another ultra-thin grounded she...

A saturable absorber is a nonlinear functional material widely used in laser and photonic nanodevices. Metallic nanostructures have prominent saturable absorption (SA) at the plasmon resonance frequency owing to largely enhanced ground state absorption. However, the SA of plasmonic metal nanostructures is hampered by excited-state absorption processes at very high excitation power, which usuall...

In this paper, we propose a novel microfluidic tunable metamaterial (MM) absorber printed on a paper substrate in silver nanoparticle ink. The metamaterial is designed using a periodic array consisting of square patches. The conductive patterns are inkjet-printed on paper using silver nanoparticle inks. The microfluidic channels are laser-etched on polymethyl methacrylate (PMMA). The conductive...

Light absorption is a fundamental optical process playing significantly important role in wide variety of applications ranging from photovoltaics to photothermal therapy. Semiconductors have well-defined absorption bands with low-energy edge dictated by the band gap energy, therefore it is rather challenging to tune the absorption bandwidth of semiconductors. However, resonant absorbers based o...