  A metamaterial composed of thin metallic strips as an efficient broadband
absorber in the mid-infrared spectrum is investigated. Here the matching
between dielectric and geometrical properties of the individual elements is
critical to ensure high absorption. Detailed theoretical analysis based on the
electric dipole approximation is performed to characterize the absorption and
scattering properties of the individual elements of the unit cell and the
results are used to design the metamaterial composed of such configurations.
The absorption cross-section of a strip-shaped element can exceed its
longitudinal geometrical cross-section area by 17 times. It was shown that the
absorptance of the Ni-based metal-insulator-metal (MIM) metamaterial structure
can exceed 90 % in about 8.2 - 18 um spectrum. The broadband absorption is
associated with the excitation of the low-Q-factor dipole modes of the strips.
Such an absorber demonstrates good polarization and incident angle tolerance
for transverse-electric (TE) waves. The absorption spectrum can be tuned by
varying individual element parameters.
