We propose the design of anisotropic metamaterials with cascading meta-atoms.Each meta-atom array behaves as an impedance-tuned interface and dramatically modifies the complex reflection and transmission coefficients....We propose the design of anisotropic metamaterials with cascading meta-atoms.Each meta-atom array behaves as an impedance-tuned interface and dramatically modifies the complex reflection and transmission coefficients.By engineering the frequency-dependent impedances,the reflection phase difference along the two axes of anisotropic metamaterials approximates to a constant in a wide range.We numerically demonstrate the proposed anisotropic metamaterials can accomplish achromatic polarization transformation from 0.5 THz to 3.1 THz.The polarization conversion ratio is higher than 80%,which exhibits excellent agreements with the theoretical calculation.Such design is scalable to other bands and can provide helpful guidance in broadband devices design.展开更多
Real-time terahertz(THz)imaging offers remarkable application possibilities,especially in the security and medical fields.However,most THz detectors work with scanners,and a long image acquisition time is required.Som...Real-time terahertz(THz)imaging offers remarkable application possibilities,especially in the security and medical fields.However,most THz detectors work with scanners,and a long image acquisition time is required.Some thermal detectors can achieve realtime imaging by using a focal plane array but have the drawbacks of low sensitivity due to a lack of suitable absorbing materials.In this study,we propose a novel photomechanical meta-molecule array by conveniently assembling THz meta-atom absorbers and bi-material cantilevers together,which can couple THz radiation to a mechanical deflection of the meta-molecules with high efficiency.By optically reading out the mechanical deflections of all of the meta-molecules simultaneously,real-time THz imaging can be achieved.A polyimide sacrificial layer technique was developed to fabricate the device on a glass wafer,which facilitates the transmission of a readout light while the THz wave radiates onto the meta-molecule array directly from the front side.THz images and video of various objects as well as infrared images of the human body were captured successfully with the fabricated metamolecule array.The proposed photomechanical device holds promise in applications in single and broadband THz as well as infrared imaging.展开更多
基金supported in part by National Science Foundation(NSF)
文摘We propose the design of anisotropic metamaterials with cascading meta-atoms.Each meta-atom array behaves as an impedance-tuned interface and dramatically modifies the complex reflection and transmission coefficients.By engineering the frequency-dependent impedances,the reflection phase difference along the two axes of anisotropic metamaterials approximates to a constant in a wide range.We numerically demonstrate the proposed anisotropic metamaterials can accomplish achromatic polarization transformation from 0.5 THz to 3.1 THz.The polarization conversion ratio is higher than 80%,which exhibits excellent agreements with the theoretical calculation.Such design is scalable to other bands and can provide helpful guidance in broadband devices design.
基金This study was funded by the National Natural Science Foundation of China(Grants No.61575003)the China Postdoctoral Science Foundation(Grants Nos.2015M580096 and 2017T100074).
文摘Real-time terahertz(THz)imaging offers remarkable application possibilities,especially in the security and medical fields.However,most THz detectors work with scanners,and a long image acquisition time is required.Some thermal detectors can achieve realtime imaging by using a focal plane array but have the drawbacks of low sensitivity due to a lack of suitable absorbing materials.In this study,we propose a novel photomechanical meta-molecule array by conveniently assembling THz meta-atom absorbers and bi-material cantilevers together,which can couple THz radiation to a mechanical deflection of the meta-molecules with high efficiency.By optically reading out the mechanical deflections of all of the meta-molecules simultaneously,real-time THz imaging can be achieved.A polyimide sacrificial layer technique was developed to fabricate the device on a glass wafer,which facilitates the transmission of a readout light while the THz wave radiates onto the meta-molecule array directly from the front side.THz images and video of various objects as well as infrared images of the human body were captured successfully with the fabricated metamolecule array.The proposed photomechanical device holds promise in applications in single and broadband THz as well as infrared imaging.
