Showing posts with label modulators. Show all posts
Showing posts with label modulators. Show all posts

Wednesday, April 29, 2020

Abstract-Total Internal Reflection Geometry: Exploiting Total Internal Reflection Geometry for Terahertz Devices and Enhanced Sample Characterization


Qiushuo Sun, Xuequan Chen, Xudong Liu, Rayko I. Stantchev, Emma Pickwell‐MacPherson

https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.201900535

To promote potential applications of terahertz (THz) technology, more advanced functional THz devices with high performance are needed, including modulators, polarizers, lenses, wave retarders, and antireflection coatings. This work summarizes recent progress in THz components built on functional materials including graphene, vanadium dioxide, and metamaterials. The key message is that, while the choice of materials used in such devices is important, the geometry in which they are employed also has a significant effect on the performance achieved. In particular, devices operating in total internal reflection geometry are reviewed, and it is explained how this geometry is able to be exploited to achieve a variety of THz devices with broadband operation.

Thursday, March 23, 2017

Abstract-Switchable broadband terahertz absorber/reflector enabled by hybrid graphene-gold metasurface



Yu Tong Zhao, Bian Wu, Bei Ju Huang, and Qiang Cheng

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-7-7161



Numerous studies have been made to design switchable terahertz absorber for the application of amplitude modulator. However, it is still a challenge to achieve large modulation range while maintaining broad bandwidth. Here, we propose a switchable broadband absorber/reflector in the low-terahertz regime. By utilizing a hybrid graphene-gold metasurface on SiO2/pSi/PDMS substrate with an aluminum back, an excellent absorption across 0.53–1.05 THz with a wide incident angles for both TE and TM polarizations is achieved. By controlling the voltage across gold electrode and pSi, the chemical potential of graphene can be changed correspondingly. When the chemical potential of graphene varied from 0eV to 0.3eV, the state of the proposed structure can be switched from absorption (>90%) to reflection (>82%) over the whole operation bandwidth. Electric field intensity and surface loss density of the proposed absorber under different chemical potential are given to have a physical insight of the mechanisms. The switchable absorber/reflector can enable a wide application of high performance terahertz devices, such as active camouflage, imaging, modulators and electro-optic switches.
© 2017 Optical Society of America