An Ultrabroadband THz Absorber Based on Structured Doped Silicon With Antireflection Techniques

Abstract

Broadband absorber in the terahertz region (0.1-10 THz) has attracted considerable attentions due to its important applications in detecting, imaging, and electromagnetic stealth. Recently, terahertz absorber with broadband features has been widely investigated, however, the achievement of ultrabroad bandwidth is still challenging due to the limitations of complex structural design and fabrication processes. In this paper, an ultrabroadband terahertz absorber covering the entire terahertz regime (0.1-10 THz) based on the heavily doped silicon has been designed and fabricated, which is composed of double-layer binary gratings filled with the SU-8 photoresist. Antireflection techniques (SU-8 layer) were utilized to further promote the performance of the terahertz absorber at high frequencies through matching the impedance between free space and doped-silicon substrate. The measured absorption exceeding 87% within the frequency range of 0.3-10 THz has verified the proposed approach in designing the ultrabroadband terahertz absorber. Furthermore, the designed absorber remains high performance in the case of wide-angle incidence even up to 60°. Benefiting from the simple structure, the absorber is easy to be fabricated by common optical lithography. We believe that the results of this paper could broaden the application areas of terahertz absorbers.

Single‐Layered Reflective Metasurface Achieving Simultaneous Spin‐Selective Perfect Absorption and Efficient Wavefront Manipulation

“…Although subsequent experiments are not performed in the presented work, many related works have been demonstrated that the fabrication of the designed sample can be achieved with low cost and high precision. [39,40] To illustrate this issue, a feasible fabrication process is schematically proposed in Figure S6 in the Supporting Information. Besides, it should be mentioned that although the proposed meta molecule shares similar structural profile to previous works for asymmetric transmission (AT), [40,41] the working mechanism is quite different.…”

Reconfigurable Continuous Meta-Grating for Broadband Polarization Conversion and Perfect Absorption

“…While broadband perfect absorption can still be realized when the GST changes to C-state. Moreover, although subsequent experiments were not performed in the presented work, many related works have proven that the fabrication of the designed metasurfaces can be implemented with a low cost and high precision [ 47 , 48 ]. Previous works also demonstrated that the crystallization and re-amorphization of GST can be successfully achieved by several methods [ 49 , 50 , 51 ], such as thermal annealing, electrical stimulus, and laser pulse illumination.…”

Phase Change Metasurfaces by Continuous or Quasi-Continuous Atoms for Active Optoelectronic Integration

“…Furthermore, to conquer the narrow band nature of early MIM absorber, broadband absorption was realized by the hybridized design of multiple meta-atoms [ 124 ]. To name a few, exquisite schemes by Luo’s group and others were used to construct the extremely broadband perfect absorption, e.g., dispersion engineering [ 1 , 125 , 126 ], the impedance matching [ 127 ] and diffraction/interference engineering [ 7 , 8 , 128 ] etc.…”