Abstract-Fabrication of anti-reflective micro-structure at terahertz frequency by using Chinese acupuncture needles

YunZhou Li, Bin Cai, and Yiming Zhu
https://www.osapublishing.org/ol/abstract.cfm?uri=ol-40-12-2917

A terahertz (THz) anti-reflective structure on a polystyrene layer was fabricated by using a handmade metallic mold comprising a bunch of Chinese acupuncture needles. Polystyrene was spin-coated onto a silicon substrate and then deformed by the mold via a hot-embossing process. The deformed layer yielded gradient refractive index profiles on the substrate. Compared with a common single antireflective layer, we observed an increase of ∼20% in the transmittance. We also observed broader bandwidth properties compared with the single layer structure. The process imposes no substrate limiting, i.e., it can be applied onto various THz device surfaces for antireflection purpose.

© 2015 Optical Society of America

Full Article  |  PDF Article

Abstract-Ultra-broadband terahertz perfect absorber by exciting multi-order diffractions in a double-layered grating structure

Ultra-broadband terahertz perfect absorber by exciting multi-order diffractions in a double-layered grating structure Yan Peng, XiaoFei Zang, YiMing Zhu, Cheng Shi, Lin Chen, Bin Cai, and SongLin Zhuang  »View Author Affiliations

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-23-3-2032

Optics Express, Vol. 23, Issue 3, pp. 2032-2039 (2015)
http://dx.doi.org/10.1364/OE.23.002032

View Full Text Article

Enhanced HTML    Acrobat PDF (1993 KB)

Terahertz (THz) perfect absorber, as a useful functional device, has attracted considerable attention. Traditional metamaterial perfect absorbers are usually in response to single-frequency or multi-frequency owing to the resonance features of the metal-based sub-wavelength structure. In this paper, a simple double-layered doped-silicon grating structure was designed to realize an ultra-broadband and polarization-independent THz perfect absorber. Both theoretical and experimental results demonstrate that the incident THz waves ranging from 0.59 to 2.58 THz can be efficiently absorbed with an absorptivity of more than 95% and a bandwidth of about 2.0 THz. The excellent characteristic of this broad-bandwidth THz perfect absorber is mainly resulted from the air gap mode resonance together with the first-order and the second-order grating diffractions.

© 2015 Optical Society of America

Abstract-Rotatable illusion media for manipulating terahertz electromagnetic waves

XiaoFei Zang, Zhou Li, Cheng Shi, Lin Chen, Bin Cai, YiMing Zhu, Li Li, and XiaoBin Wang  »View Author Affiliations

http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-21-25565

Abstract

Based on composite optical transformation, we propose a rotatable illusion media with positive permittivity and permeability to manipulate terahertz waves, and a new way to realize singular parameter-independent cloaks when the incident wave with a certain width propagates from specific incident directions. The fundamental mechanism of this kind of cloak is that the illusion media can be able to avoid the incident wave interacting with the objects. Comparing with traditional transformation-coordinate-based cloaks such as cylindrical-shaped cloaks, our cloaks are independent of singular material parameters. Furthermore, this type of rotatable illusion media can be applied to design tunable miniaturized high-directivity antenna (a small antenna array covered with the rotatable illusion media appears like a large one and meanwhile, the radiation directions of the small antenna array is tunable via this rotatable illusion media). Full wave simulations are performed to confirm these points.

© 2013 Optical Society of America