Abstract-Distinctive Performance of Terahertz Photodetection Driven by Charge‐Density‐Wave Order in CVD‐Grown Tantalum Diselenide

Lin Wang,  Jin Wang,  Changlong Liu,   Huang Xu,  Ang Li,  Dacheng Wei,   Yunqi Liu,  Gang Chen,  Xiaoshuang Chen,  Wei Lu,

https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.201905057?af=R

The quantum behavior of carriers in solid is the foundation of modern electronic and optoelectronic technology, but it is still facing huge challenges within inherited single‐particle quantum processes working at the millimeter wave/terahertz (THz) band. Here, a straightforward strategy for the direct detection of millimeter wave/THz photons in a sub‐wavelength metal‐TaSe2‐metal structure under strong interaction with a localized field of surface plasmon is proposed. By breaking the inversion symmetry under the perturbations of electric field and atomic reconstruction from van der Waals integration, the nonequilibrium electronic states under a radiant field can be manipulated in a collective fashion, leading to a large photocurrent responsivity over 40 A W−1 and noise equivalent power less than 1 pW Hz−1/2 even at room temperature. A more than 40‐fold enhancement in responsivity is achieved when transitioning from the normal phase to the CDW phase. The findings shed fresh light on the understanding of the delicate balance in the charge‐ordered phase, and facilitate the exploitation of a correlated electron system for optoelectronic applications in fields of security, remote sensing, and imaging.

Abstract-Tunable terahertz toroidal response by graphene metamaterials

Materials Research Express

Ya-Qian Zhang, Jie Li, Ren-chao Jin, Jiaqi Li, Jin Wang, Zheng-Gao Dong

https://iopscience.iop.org/article/10.1088/2053-1591/ab1580/pdf

We present the toroidal dipolar response in graphene-based disk metamaterials at terahertz range and find that this response has a dominant role over traditional multipoles, attributed to the atom-level ultrathin characteristic of graphene. Moreover, the toroidal response is tunable with the Fermi level of graphene, readily to be realized by applying electrostatic gating, photo-injection, etc. Layers of graphene also obviously influence the toroidal response in terms of the resonant frequency and magnitude. It is believed that the actively tunable characteristic in graphene metamaterials, in contrast to noble-metal-based metastructures, will provide potentials for future terahertz devices based on toroidal response.

Abstract-Graphene-based broadband terahertz detector integrated with a square-spiral antenna

Wanlong Guo, Lin Wang, Xiaoshuang Chen, Changlong Liu, Weiwei Tang, Cheng Guo, Jin Wang, and Wei Lu

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-43-8-1647

Raising interest in terahertz radiation (loosely defined as the 0.1∼10  THz$0.1\sim 10\mathrm{THz}$ frequency range) for the application-oriented issues in everyday life requires progressive development of fast, sensitive, and portable photodetectors. In this Letter, a broadband graphene-based terahertz detector with good integrability and sensitivity at room temperature is proposed. It is based on the chemical vapor deposited-grown graphene integrated with a square-spiral metal antenna which, on one hand, improves the efficiency for electromagnetic coupling and, on the other hand, facilitates the hot-electron photo-thermoelectric process for photodetection. Sensitivity over 28 V/W at room temperature and noise-equivalent power of less than 0.35  nW/Hz0.5$0.35\mathrm{nW}/{\mathrm{Hz}}^{0.5}$ are demonstrated in reference to the incident power. The presented results appealingly open an alternative way to realize chip-level graphene-based terahertz optoelectronics with good scalability and expected performance for targeted terahertz applications.

© 2018 Optical Society of America