Abstract-Graphene plasmonics for surface enhancement near-infrared absorptivity

QingHui Pan, JiaRong Hong, GuoHua Zhang, Yong Shuai, and HePing Tan


https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-14-16400&origin=search

Monolayer graphene has poor absorption in the near-infrared region. Its layer is only as thick as a single atom so it cannot have a high absorptivity. In this paper, in order to form a hybrid system, the absorption characteristics of monolayer graphene covering a metal/dielectric/metal substrate has been theoretically analyzed. The magnetic polaritons in the metal/dielectric couple with the plasmonic resonance in the graphene to dramatically enhance the graphene absorptivity. This study analyzes the factors that enhance the absorptivity, including the geometric parameters and the relative positions of the graphene. The local electromagnetic field and the power dissipation density are illustrated to explain the underlying mechanisms further. These numerical results can provide potential application in the field of optical detection and optoelectronic devices.

© 2017 Optical Society of America

Abstract-An ultrathin terahertz lens with axial long focal depth based on metasurfaces

Xiao-Yan Jiang,¹ Jia-Sheng Ye,^1,2,* Jing-Wen He,^1,3 Xin-Ke Wang,^1,2 Dan Hu,^1,3 Sheng-Fei Feng,^1,2 Qiang Kan,⁴ and Yan Zhang^1,2,3,5

¹Department of Physics, Capital Normal University and Beijing Key Lab for THz Spectroscopy and Imaging, Key Lab of THz Optoelectronics, Ministry of Education, Beijing 100048, China

²Beijing Center for Mathematics and Information Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150001, China

³Department of Physics, Harbin Institute of Technology, Harbin 150001, China

⁴State Key Laboratory for integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China

⁵yzhang@mail.cnu.edu.cn

^*Corresponding author: jiashengye@gmail.com

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-21-24-30030

The plasmonic resonance effect on metasurfaces generates an abrupt phase change. We employ this phase modulation mechanism to design the longitudinal field distribution of an ultrathin terahertz (THz) lens for achieving the axial long-focal-depth (LFD) property. Phase distributions of the designed lens are obtained by the Yang-Gu iterative amplitude-phase retrieval algorithm. By depositing a 100 nm gold film on a 500 μm silicon substrate and etching arrayed V-shaped air holes through the gold film, the designed ultrathin THz lens is fabricated by the micro photolithography technology. Experimental measurements have demonstrated its LFD property, which basically agree with the theoretical simulations. In addition, the designed THz lens possesses a good LFD property with a bandwidth of 200 GHz. It is expected that the designed ultrathin LFD THz lens should have wide potential applications in broadband THz imaging and THz communication systems.
© 2013 Optical Society of America