Research On Tunable Absorber Based On The Composite Metamaterial Of Indium Antimonide

Terahertz(THz)wave,electromagnetic radiation between microwave and far infrared,is not developed or utilized to the best advantage.Electromagnetic metamaterials based on subwavelengths offer greater latitude with the terahertz wave control.Compared with the traditional materials,metamaterials have the electromagnetic features with obvious advantages,of which electromagnetic response depends only on the periodic structure.Especially in the terahertz regime,the metamaterials absorbers(MMAs)provide a perfect absorption,small volume and so on,which have some exciting applications in the field of biosensor and energy absorptive.A fixed operating frequency will be achieved when the period structure of traditional MMAs is determined,which limits functionality to some degree.The permittivity of indium antimonide(In Sb)is temperature-sensitive in the terahertz region,hence the MMAs will be endowed with active control when integrating the In Sb into the MMAs design.We designed two types of multi-band MMAs and one singleband MMAs,which based on the In Sb with tunable optical properties,employing electromagnetic simulation software to study the properties and physical mechanism.Specific research ideas are as follows:Firstly,a five-band terahertz MMAs is designed based on the method of metal microslot.Previous studies have suggested that metal resonator unit with micro-slot would excite the high-order resonance mode,and a multi-band MMAs would be achieved by the parameter optimization of the structure.The MMAs adopt three layers with metal-In Sbmetal.The results indicate that the MMAs has five perfect absorption band,which can be turned by temperature controlling.The symmetrical structure endowed the MMAs with polarization insensitivity.In addition,compared to traditional multi-band absorbers combining various metal resonator units,the proposed MMAs have the advantages of ultrathin and small size,which is beneficial to the development of miniaturization and integration of optical devices.Secondly,we designed a quad-band terahertz MMAs with independent frequency and amplitude modulations,the MMAs is a three-layered metal-In Sb-hybrid metasurface,and the hybrid metasurface is composed of metal and silicon.The simulation results present that the four absorption peaks is as close to perfect absorption.When the temperature is 250 K,the conductivity of the silicon is changed from 0 to 64000S/m by controlling the pump power,the similar trend at the change of four absorption peaks ranges from 10.61% to 99.01%.In addition,the tuning range of working frequency is 0.875THz?6.419 THz as external temperature ranging from 190 K to 350 K,and the four-band with continuous modulation offer an operation frequency of ultra-wideband with 5.544 THz.Finally,an empirical equation is obtained for explaining the relationship between the four center frequency and temperatures,which provide references for the MMAs' design.Finally,a tunable MMAs with high-Q property is designed based on the all-dielectric resonator(In Sb).The effects of different polarizations,incident angles and structural parameters on the performance of the MMAs are analyzed.The explanation for the physical mechanism is presented by analyzing the electric field distribution of the MMAs.In addition,the tuning performance of the MMAs is studied under different temperatures,the results show the MMAs provide flexible methods for tuning the absorption channel from 5.47 THz to 6.35 THz,the average absorptivity is 99.24%,and the Q value of the lowest resonance absorption peak retains 99.9.