Research On Graphene Tunable Terahertz Absorber

Graphene has unique electronic and mechanical properties in the terahertz,such as dynamically tunable conductivity,low loss,high constraint and support for surface plasmon polaritons.Graphene has been widely used in various fields of terahertz research,especially in the field of tunable terahertz absorbers.By designing the graphene structure,the graphene terahertz absorber can achieve nearly perfect absorption.In this paper,the study focus on graphene tunable terahertz absorbers,the numerical calculation and theoretical analysis of graphene absorbers are studied.The main research include:A single band graphene tunable terahertz absorber is designed.The absorption performance and internal mechanism of the absorber are comprehensively analyzed and the peak frequency of the single band of the absorber can be tuned by changing the graphene Fermi level E_f:When E_f=0eV,the absorption of the absorber reaches99.99%at the 0.48THz,when E_f=0.2eV,the absorption of the absorber reaches99.96%at 1.37THz.When E_f=0.4eV,the absorption of the absorber reaches 99.83%at 1.44THz.When E_f=0.6eV,the absorption of the absorber reaches99.5%at1.579THz.In addition,an equivalent circuit model for the single band graphene tunable terahertz absorber is innovatively proposed,and the calculation formulae of the relevant electronic components of the equivalent circuit is derived.The numerical calculation results of single band graphene tunable terahertz absorber are basically consistent with the result of the equivalent circuit model.A dual band graphene tunable terahertz absorber is designed,and the absorber is numerically and theoretically analyzed.The peak frequency of the dual band absorber can be tuned by changing the graphene Fermi level E_f:When E_f=0eV,the absorption reaches 87%at 0.69THz,and the absorption reaches 96%at 1.61THz;When E_f=0.1eV,the absorption reaches 99.6%at 0.68THz,and the absorption reaches 99.4%at 1.63THz.When E_f=0.2eV,the absorption reaches 95%at 0.71THz,the absorption reaches 93%at 1.69THz.In addition,the effect of geometry of the absorber on absorber performance is analyzed.The dual band graphene tunable terahertz absorber has a simple structure and excellent absorption performance and is tunable flexibly.A broadband graphene tunable terahertz absorber is designed.Detailed numerical calculations and theoretical analysis of the absorber are performed,The peak frequency of the broadband absorber can be tuned by changing the graphene Fermi level E_f:when E_f=0.1eV,the absorber achieves 0.65THz bandwidth with absorption exceeding 90%from 0.65THz to 1.3THz;when E_f=0.2eV,the absorber achieves0.64 THz bandwidth with absorption exceeding 89.5%from 0.66 THz to 1.30THz;when E_f=0.3eV,the absorber achieves 0.5THz bandwidth with absorption excessing89%from 0.72THz to 1.32THz.In addition,the internal mechanism of the broadband graphene tunable terahertz absorber is analyzed using the transmission line theory,and the absorber performance curve achieved by theoretical calculation is in good agreement with the absorber performance curve achieved by numerical calculation.