An Ultra-Wideband THz/IR Metamaterial Absorber Based on Doped Silicon

Abstract

Metamaterial-based absorbers have been extensively investigated in the terahertz (THz) range with ever increasing performances. In this paper, we propose an all-dielectric THz absorber based on doped silicon. The unit cell consists of a silicon cross resonator with an internal cross-shaped air cavity. Numerical results suggest that the proposed absorber can operate from THz to far-infrared regimes, having an average power absorption of ∼95% between 0.6 and 10 THz. Experimental results using THz time-domain spectroscopy show a good agreement with simulations. The underlying mechanisms for broadband absorption are attributed to the combined effects of multiple cavities modes formed by silicon resonators and bulk absorption in the doped silicon substrate, as confirmed by simulated field patterns and calculated diffraction efficiency. This ultra-wideband absorption is polarization insensitive and can operate across a wide range of the incident angle. The proposed absorber can be readily integrated into silicon-based photonic platforms and used for sensing, imaging, energy harvesting and wireless communications applications in the THz/IR range.

Recent Advances in the Development of Materials for Terahertz Metamaterial Sensing

“…[ 122 ] Recently, silicon‐based plasmonic MPAs have attracted much attention because of their ability to be easily incorporated into silicon‐based platforms using the existing complementary metal–oxide–semiconductor (CMOS) technology with tunable broadband characteristics. [ 122–130 ] Fan et al. fabricated a silicon‐based terahertz metamaterial absorber containing a cylinder array ( Figure a).…”

“…and Liu et al. proposed an ultrawideband silicon‐based terahertz metamaterial absorber with an optically tunable peak absorbance over 99% (Figure 12b,c), [ 122,123 ] which could be operated across a wide range of the incident angles at terahertz frequencies. Wang et al.…”

“…b) An all‐dielectric terahertz absorber containing doped silicon, which was developed by Hu and co‐workers. [ 123 ] Adapted under the terms of the Creative Commons Attribution License. [ 123 ] Copyright 2018, MDPI.…”

“…[ 123 ] Adapted under the terms of the Creative Commons Attribution License. [ 123 ] Copyright 2018, MDPI. c) A single‐layer H‐shaped all‐silicon array terahertz perfect absorber fabricated by Zhang and co‐workers.…”

Flexible Ultra-Wideband Terahertz Absorber Based on Vertically Aligned Carbon Nanotubes

“…[10][11][12][13][14] Another approach utilizes intrinsic high loss dielectrics or semiconductors to achieve wideband absorption using relatively simpler structures. [15][16][17][18][19] However, the former approach faces an increased design and fabrication complexity, while the latter still shows dependence on the properties of lossy dielectrics it uses. In addition to MPAs, one possible strategy for achieving ultra-wide band absorption performance is to use low reflective surface structures with a high lossy skeleton material.…”