Tunable THz absorption using Al/SiOx planar periodic structures

To increase the sensitivity of uncooled microbolometer-based THz imagers, absorbing structures (metamaterial films) with resonant absorption that can be tuned to a QCL illuminator frequency are investigated. The metamaterial films are comprised of periodic arrays of aluminum (Al) squares and an Al ground plane separated by a thin silicon-rich silicon oxide (SiOx) dielectric film. Finite element simulations were performed by varying the structural parameters to establish the design criteria for high absorption, spectral tunability and bandwidth. Several structures with single band and multiband absorption characteristics were fabricated. Measured absorption spectra show absorption up to 100% at designed THz frequencies and the spectral characteristics agree with simulations.

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