The Study Of Metal/Dielectric Multilayer Microstructured Absorbers

With the continuous progress of precision processing technology and growth technology,modern optical devices are rapidly developing towards precision and miniaturization,and micro-nano optical devices have also attracted widespread attention.Since Landy et al.first proposed a metamaterial near perfect absorber?MPA?,metamaterial absorbers have gradually become a hot field in micro-nano optics.As an important branch of the metamaterial absorbers,the metal/dielectric multilayer nanostructured absrobers have great application value and development prospect.So far,many efforts have been made to improve the light absorption of metal/dielectric multilayer microstructured absorbing devices.The absorption characteristics have also expanded from the original single-band to multi-band,broadband,wide-angle incidence,polarization insensitivity and so on.Combined with the current mature manufacturing technology,metal/dielectric multilayer microstructured absorbers have been widely used in various fields.Based on the Finite-Difference Time-Domain?FDTD?method,this paper performs theoretical calculations and analysis of several novel metal/dielectric multilayer microstructured absorbers.The main research contents are as follows:1.A novel dual-band absorber is proposed to enhance light absorption by using a hyperbolic rectangular array?HRA?.The enhanced light absorption of the HRA results from the propagating surface plasmon?PSP?resonance,and double absorption bands with peak absorption of?95%in the visible-to-near-infrared region can be obtained.The selective absorption characteristic of the structure comes from the hyperbolic dispersion characteristic.The absorption spectrum of the HRA is estimated by the effective medium theory?EMT?,and with the increase of the number of film stack,the absorption spectrum of the actual structure is getting closer to the absorption spectrum of EMT.The dual-band absorption is very robust to the variations of the width and the number of film stack and good refractive index sensing performance can be achieved by using two absorption bands.2.Dual-band light absorption enhancement of monolayer molybdenum disulfide?MoS₂?is proposed by using periodic dielectric wires.The light absorption enhancement of monolayer MoS₂ results from Mie resonance and the absorptions of monolayer MoS₂ are significantly enhanced up to 93.7%and 94.6%at resonance wavelengths,respectively.The evolution of the selective absorption properties of the MoS₂-based structure are evaluated by using the impedance theory and the waveguide theory.In addition,good absorption features of monolayer MoS₂ can be maintained as the top and bottom widths of the dielectric wire are significantly altered.3.An ultra-broadband absorber based on metal-dielectric periodic film stack and metal microstructure arrays is proposed and demonstrated experimentally.Due to the excitation of the PSP resonance and the gap plasmon polariton?GPP?resonance,the proposed ultra-broadband absorber can achieve nearly perfect absorption in a wide band of 380-2158.7nm,with an average absorption efficiency of 96.5%.In order to better understand the near-perfect absorption characteristics of ultra-broadband absorber,impedance theory is introduced to evaluate the spectral characteristics of the absorber.In addition,the proposed ultra-broadband absorber exhibits excellent angle-insensitivity and polarization-independent characteristics,and the metal material used is not a precious metal such as gold or silver,which has low production cost and extremely high production tolerance.