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In this paper, we propose an Insulator-Metal-Insulator-Metal (IMIM) nano-block array structure, which can achieve tunable single-peak and double-peak perfect absorption properties from visible light to near-infrared. Compared with our previous work, this paper additionally points out that due to the coupling effect between SPPs, the original blue-shifted spectrum is converted into red-shifted during the process of changing the thickness ratio of the middle silver nano-block to the SiO2 nano-block. In the design parameter range, two different structural parameters can be found, in which the absorption peak is exactly the same, and the short-wave absorption peak position has the characteristics of "on" and "off". Based on the nature of absorption spectrum, it can be applied to optical switches in optical circuits. And this work also provides a new idea for plasma sensors, which has broad application prospects in the fields of filtering and imaging. [ABSTRACT FROM AUTHOR]

A broadband near-infrared (NIR) absorption from 1200 to 2500 nm in Si substrate is investigated by Ag film deposition and subsequent thermal annealing. Under thermal annealing, Ag films can crack and shrink into Ag nanoparticles (NPs). Annealing temperature greatly affects the size, distribution status and morphology of Ag NPs, resulting in different NIR absorption. The influence of the size and distribution of Ag NPs on NIR absorption originated from localized surface plasmon resonance (LSPR) is theoretically simulated by a finite difference time domain method. The band width of LSPR belongs to different type Ag NPs are discussed. [ABSTRACT FROM AUTHOR]

We design a deep-trench microstructure covered with thin gold films to enhance near-infrared absorption of silicon material. This deep-trench microstructure exhibits a much higher absorption compared with plane nanoantenna arrays. We investigate its absorption enhancement in detail and find that the trench-shaped plasmonic waveguide greatly contributes an absorption enhancement by concentrating light effectively. Further, we clarify the influence of both trench depth and gold films covering on different positions of deep trench on the absorption. Finally, we use surface plasmon polaritons offered by plasmonic waveguide to explain well the significant enhancement of near-infrared absorption. [ABSTRACT FROM AUTHOR]

We present a meta-cone absorber based on metamaterials which can absorb nearly all incident light in the near-infrared spectrum. The absorber has an ultrahigh absorption with a broad receiving angle and independence of polarization state. This absorption enhancement can be attributed to the excitation of slow light mode and localized surface plasmon resonances (LSPR). In addition, we use slow light theory to explain why incident light with different wavelengths are trapped at different positions. We believe our work will provide a promising candidate as absorbing elements in technical applications and scientific research. [ABSTRACT FROM AUTHOR]