Design,Fabrication,and Application Of Terahertz Graphene Metamaterials Devices

The spectrum of Terahertz（THz）is between the microwave and infrared band,which has many advantages,such as low energy,strong penetrability,and wide band.Consequently,the demand of the THz function devices is becoming more and more urgent.Metamaterials are artificial electromagnetic materials which is composed of artificially designed subwavelength structure units,and possesses extraordinary physical properties that natural materials do not have.The emergence of metamaterials has prompted the development of THz sensing,detection and functional devices.However,the traditional THz metamaterial devices tend to be fabricated by complicated and costable lithography process,which considerably restricts the development of THz metamaterial devices.In order to solve the above problems,this paper integrates the laser-induced process into the field of THz metamaterial device processing,and a THz metamaterial band-stop filter based on laser-induced graphene（LIG）is designed and fabricated.Furthermore,a multifunctional visual THz detector is designed in combination with a temperature sensitive cholesteric liquid crystal microcapsule（CLCM）.Firstly,the preparation methods of LIG is introduced and the microstructure and intrinsic information of LIG are characterized.It focuses on the conductivity and the THz transmission of LIG materials under different laser parameters.The simulation and experiment results preliminary verifies the linear relationship between the LIG electrical conductivity and the THz transmission,and clarifies the adaptability of LIG material in THz band.Then,a THz metamaterial filter with a disk unit structure is proposed,and further optimizes various parameters of the unit structure to determine the processing parameters.An ultrathin,flexible metamaterial filter operated at THz frequencies based on one-step CO₂ LIG is proposed.The experimental results indicates that the modulation depth reaches 63%at a frequency of 0.67 THz.The filter’s-3 dB bandwidth is～0.11 THz and the Q value is 6.09.Besides,it is also shown that the simulation results match the experiment result.Moreover,when the filter is under different bending conditions,the filtering performance does not change much,which demonstrates its great stability.Finally,a temperature-sensitive CLCM is briefly introduced,and the microscopic temperature is visually detected by combining CLCM with LIG,which confirms the excellent thermal conductivity of LIG.Subsequently,this paper proposes a multifunctional visual THz detector structure,and preliminary realization of the purpose of THz wavelength division frequency detection.The LIG method thus offers a one-step,large-area,and fast approach without masks for fabricating cost-effective,reliable,and flexible carbon-based metamaterial THz devices,which are expected to be applicable to various purposes,ranging from THz communication to THz biological detection and sensing in the near future.