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In this work, we give a detailed experimental and theoretical analysis of a nano cone array on silicon wafer, which can greatly enhance the absorption compared with the polished silicon. The experimental absorptance can reach 98.7% in the wavelength ranging from 400 nm to 1100 nm. The mechanism of absorption enhancement is attributed to the nano cone array that can suppress the reflection by building a grade index from air to silicon surface. Moreover, an ultrathin 13 nm thickness gold film was sputtered on the nano cone array, by which surface plasmon can be excited and the absorption in the near-infrared region can be greatly enhanced. We also give a deep comprehending on the physics mechanism of such high absorption. This kind of nano cone array can be fabricated by a simple and low-cost colloidal sphere lithography and reactive ion etching, which makes it a more appropriate candidate for photovoltaics, spectroscopy, photodetectors, sensor, especially for the silicon-based application in the near-infrared region. [ABSTRACT FROM AUTHOR]

We propose a metal-dielectric-metal super absorber based on propagating and localized surface plasmons which exhibits a near perfect absorption in the visible and near-infrared spectrum. The absorber consists of Ag/AlO/Al triple layers in which the top Al layer is a periodic nano disk array. The absorption spectrum can be easily controlled by adjusting the structure parameters including the period and radius of the nano disk and the maximal absorption can reach 99.62 %. We completely analyze the PSPs and LSPs modes supported by the MDM structure and their relationship with the ultrahigh absorption. Moreover, we propose a novel idea to further enhance the absorption by exciting the PSPs and high-order LSPs modes simultaneously, which is different from the previous works. This kind of absorber using stable inexpensive Al instead of noble metal Au or Ag is an appropriate candidate for photovoltaics, spectroscopy, photodetectors, sensing, and surface-enhanced Raman spectroscopy (SERS). [ABSTRACT FROM AUTHOR]

We propose a metal-insulator-metal super absorber based on an asymmetric Fabry-Perot cavity, by which a perfect narrow-band absorption can be achieved. In this structure, two silver layers form a cavity spaced by a lossless silicon oxide layer. The absorption of the absorber can reach about 98% and its absorption peak can be tuned by altering the thickness of the middle SiO layer. We further present a deep comprehension on the physics mechanism of such high absorption. This super absorber can be easily fabricated by mature thin film technology, which make it an appropriate candidate for photodetectors, sensing, and spectroscopy. [ABSTRACT FROM AUTHOR]

In this paper, a metal-dielectric-metal structure based on a Fabry–Perot cavity was proposed, which can provide near 100% perfect narrow-band absorption. The lossy ultrathin silver film was used as the top layer spaced by a lossless silicon oxide layer from the bottom silver mirror. We demonstrated a narrow bandwidth of 20 nm with 99.37% maximum absorption and the absorption peaks can be tuned by altering the thickness of the middle SiO2 layer. In addition, we established a deep understanding of the physics mechanism, which provides a new perspective in designing such a narrow-band perfect absorber. The proposed absorber can be easily fabricated by the mature thin film technology independent of any nano structure, which make it an appropriate candidate for photodetectors, sensing, and spectroscopy. [ABSTRACT FROM AUTHOR]