Abstract-Tunable multi-band terahertz absorber based on a one-dimensional heterostructure containing semiconductor

Yang Liu,  Sheng-Qiu Xu, Ming Liu, Xin-Guang Hu, Yong-Fa Duan, Lin Yi

https://www.sciencedirect.com/science/article/pii/S0030402618307502

The absorption properties of a simple layered heterostructure composed of semiconductor and dielectric are analyzed by transfer matrix method. The numerical results indicate that such a structure can serve as a tunable multi-band terahertz perfect absorber. This phenomenon is due to the photon localization in the semiconductor layer at particular wavelengths and the presence of the damping factor of semiconductor layer. The number of the absorption peaks can be tuned by changing the thickness of the semiconductor layer. Moreover, the influences coming from the incident angle and the temperature of semiconductor on the absorption properties are also numerically studied.

Abstract-Photomechanical meta-molecule array for real-time terahertz imaging

Yongzheng Wen, Delin Jia, Wei Ma, Yun Feng, Ming Liu, Liquan Dong, Yuejin Zhao,  Xiaomei Yu

https://www.nature.com/articles/micronano201771


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 real-time 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 meta-molecule array. The proposed photomechanical device holds promise in applications in single and broadband THz as well as infrared imaging.

Abstract-Metamaterials: A New Ba0.6Sr0.4TiO3–Silicon Hybrid Metamaterial Device in Terahertz Regime

http://onlinelibrary.wiley.com/doi/10.1002/smll.201670098/full

A giant terahertz modulation based on a Ba0.6Sr0.4TiO3–silicon hybrid metamaterial is reported by L. Wu, W. Zhang, and co-workers on page 2610. The proposed nanoscale Ba0.6Sr0.4TiO3 (BST) hybrid metamaterial, delivering a transmission contrast of up to ≈79% due to electrically enabled carrier transport between the ferroelectric thin film and silicon substrate, is promising in developing high-performance real world photonic devices for terahertz technology.

Abstract-A New Ba0.6Sr0.4TiO3–Silicon Hybrid Metamaterial Device in Terahertz Regime

http://onlinelibrary.wiley.com/doi/10.1002/smll.201600276/full

Metamaterials, offering unprecedented functionalities to manipulate electromagnetic waves, have become a research hotspot in recent years. Through the incorporation of active media, the exotic electromagnetic behavior of metamaterials can be dramatically empowered by dynamic control. Many ferroelectric materials such as BaSrTiO3 (abbreviated as BST), exhibiting strong response to external electric field, hold great promise in both microwave and terahertz tunable devices. A new active Ba0.6Sr0.4TiO3–silicon hybrid metamaterial device, namely, a SRR (square split-ring resonator)–BaSrTiO3 thin film-silicon three-layer structure is fabricated and intensively studied. The active Ba0.6Sr0.4TiO3 thin film hybrid metamaterial, with nanoscale thickness, delivers a transmission contrast up to ≈79% due to electrically enabled carrier transport between the ferroelectric thin film and silicon substrate. This work has significantly increased the low modulation rate of ferroelectric based devices in terahertz range, a major problem in this field remaining unresolved for many years. The proposed BST metamaterial is promising in developing high-performance real world photonic devices for terahertz technology.