Narrowband Perfect Absorber using Metamaterials

We will continue developing a plasmonic metamaterial with strong absorption within a narrow band that is dynamically tunable over the 8-10 micron range. A metamaterial consisting of one or more bi-layers of thin metal and dielectric films will trap, concentrate and absorb a narrow frequency band while strongly reflecting out-of-band light. Tuning the frequency of the absorption band may be achieved either by MEMS actuation to change geometry, or by carrier density modulation to change the refractive index of semiconductor layers. The metamaterial may be fabricated with standard lithography techniques and processes that are compatible with microbolometer manufacturing. We believe that this plasmonic perfect absorber approach offers considerable advantages over a coupled split-ring and cut wire approach that is being pursued by other groups, because the material losses in real metals will always broaden out a resonance that relies on current loops in metals. By completion of Phase II, we will have evaluated a fully integrated plasmonic absorber microbolometer system for detecting chemical and biological agents.