Abstract
Based on calculations using the macroscopic Maxwell’s equations with mesoscopic boundary conditions, light absorption by a layered metal-insulator-metal (MIM) metamaterial system embedded in three different environments is investigated. Increasing the top metal thickness shifts the broad absorption band to lower dielectric-constant regions and longer wavelengths, for either TM or TE waves. Boosting the dielectric-layer thickness redshifts the broadband absorption to regions of larger dielectric constant. In air, for the dielectric-constant range of 0.86–3.40, the absorption of the system exceeds 98% across 680–1,033 nm. In seawater with optimized dielectric constant, ≥94% light absorption over 400–1,200 nm can be achieved; particularly in the wavelength range of 480–960 nm and dielectric-constant range of 0.82–3.50, the absorption is greater than 98%. In an environment with even higher refractive index (1.74), ≥98% light absorption over 400–1,200 nm can be achieved, giving better performance. The influence of angle of incidence on light absorption of the MIM system is also analyzed, and the angle tolerance for ≥90% broadband absorption of a TM wave is up to 40° in an environment with large refractive index. While the incident-angle dependence of the absorption of a TE wave is nearly the same for different circumstances, the situation is different for a TM wave.
© 2023 Optical Society of Korea
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