Characterizations of reconfigurable infrared metamaterial absorbers.

We propose four types of metamaterial absorbers (MAs) to have tunable absorption resonance and polarization-dependent/independent, single-band, and dual-band switch characterizations. By tailoring four types of MAs with different heights between top and bottom metal layers, absorption resonance can be modified at a 5.92 μm wavelength, and the absorption intensity can be attenuated gradually. These characteristics of MA devices can be potentially used in a variable optical attenuator (VOA). By changing the distance between the top unit cells of four devices, the resonances can be tuned in the range of a 1.74 μm wavelength with an exponential relationship. All absorption intensities can be maintained over 90%. Furthermore, MA devices also possess single-band and dual-band switch characterizations by controlling the polarization angle of incident light, which helps the MA to have the potential in a multifunctional switch. By comparing the range of switch ratios, it can be spanned 1.76 for dual-band switch function. This Letter provides a strategy to open an avenue for VOA, absorber, detector, sensor, and switch applications in the IR wavelength range.