Shanghai Opto-Mechanics made progress in broadband tunable electromagnetic absorbers

[ Instrument Network Instrument R & D ] Recently, the microstructured photophysics research team led by Zhang Long and Dong Hongxing, researchers at the Shanghai Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, and Fudan University, collaborated on large-scale broadband tunable electromagnetics. New progress has been made in absorbers, and related results were published as a front cover article in [Nanoscale, 12, 5374 (2020)].

Metamaterial electromagnetic absorbers have very important application prospects in the fields of imaging, solar cells, and sensing due to their ultra-thin size, high absorption efficiency, and highly controllable working range. Compared with traditional absorbing materials, the thickness of metamaterial absorbing devices can reach one-tenth of the wavelength or even smaller, which is very suitable for micro integrated photovoltaic systems. And its strong frequency selection characteristics make it play an important role in areas that traditional absorbing materials cannot achieve. However, most of the existing metamaterial designs are accompanied by shortcomings such as narrow bandwidth, fixed operating frequency, and expensive processing technology, which have greatly restricted their industrial application process.

In this study, the researchers used the self-assembled centimeter-sized alumina periodic nanopore structure as a mask to realize an Al nanoparticle array with a size of 1.5 × 1.5 cm 2. By designing the method of superimposing the local plasmon resonance of single-structure metal nanoparticles with cavity Fabry-Perot interference (FP) resonance absorption peaks, it has successfully achieved a broadband efficient absorption of> 80% in the near-infrared band. The phase change material germanium antimony tellurium (GST) is designed as a tunable medium material. The temperature-controlled GST refractive index change realizes a multi-gradient temperature-controllable optical function structure. In addition, the research team also simulated the experiment through finite element simulation. The simulation results are in good agreement with the experimental results, which provides a good guide for the analysis and verification of related physical mechanisms and further experimental exploration. Compared with previous work on metamaterials absorbing structures, this research for the first time solves the problems that hinder the development of metamaterials such as bandwidth, tunability, and large-scale preparation schemes. It is expected to be used in solar cells, smart sensing, imaging, and color printing in the future. And other fields have a wide range of applications.

Relevant work was supported by the National Natural Science Foundation of China and the Shanghai Young Talent Project.

Figure 1 This work was published as a front cover article of Nanoscale 2020 Volume 12 Issue 9

Figure 2 Schematic, morphological and spectral characterization of large-scale broadband absorbing structure