We propose a broadband infrared absorber by engineering the frequency dispersion of metamaterial surface (metasurface) to mimic an ideal absorbing sheet. With a thin layer of structured nichrome, a polarization-independent absorber with absorption larger than 97% is numerically demonstrated over a larger than one octave bandwidth. It is shown that the bandwidth enhancement is related with the transformation of the Drude model of free electron gas in metal film to the Lorentz oscillator model of a bound electron in the structured metallic surface. We believe that the concept of dispersion engineering may provide helpful guidance for the design of a broadband absorber.
© 2012 Optical Society of America
Original Manuscript: February 22, 2012
Revised Manuscript: March 14, 2012
Manuscript Accepted: March 15, 2012
Published: June 1, 2012
Qin Feng, Mingbo Pu, Chenggang Hu, and Xiangang Luo, "Engineering the dispersion of metamaterial surface for broadband infrared absorption," Opt. Lett. 37, 2133-2135 (2012)