摘要: In this paper, we propose a MIM (metallic metasurface-insulator-metal)
stacked structure to realize perfect absorption in mid- and far- infrared
bandwidth. A large number of metallic composite metallic units placed on a
uniform layer of insulator Ge which is deposited on a uniform metallic Ti
surface. Each of units consists of four right-angled triangular cubes in middle
of four sides of a square. Three resonant absorption peaks can be discrete or
levelling dependent to thickness of cubes. Once metallic cubes are thinner than
its skin depth, an effective ultra-broadband absorber is realizable with
average absorption over 90% percent ranging from 8-14{\mu}m. We build a
four-level cavity-dipole interacting model to explain phenomena of plasma
absorption levelling. This is created by strong phase coherence from
meta-surface since three hybrid modes are coupled by common cavity photons in
arrays of micro-cavities between top and below metallic layers. The structure
is polarization-selective to infrared light. It has great potential in infrared
detection and imaging.