Abstract-High-efficiency terahertz spin-decoupled meta-coupler for spoof surface plasmon excitation and beam steering

Li-Zheng Yin, Tie-Jun Huang, Feng-Yuan Han, Jiang-Yu Liu, Pu-Kun Liu

https://assert.pub/papers/1904.06133

Spoof surface plasmon (SSP) meta-couplers that efficiently integrate other diversified functionalities into a single ultrathin device are highly desirable in the modern microwave and terahertz fields. However, the diversified functionalities, to the best of our knowledge, have not been applied to circular polarization meta-couplers because of the spin coupling between the orthogonal incident waves. In this paper, we propose and numerically demonstrate a terahertz spin-decoupled bifunctional meta-coupler for SSP excitation and beam steering. The designed meta-coupler is composed of a coupling metasurface and a propagating metasurface. The former aims at realizing anomalous reflection or converting the incident waves into SSP under the illumination of the left or right circular polarization waves, respectively, and the latter are used to guide out the excited SSP. The respective converting efficiency can reach 82% and 70% at 0.3THz for the right and left circular polarization incident waves. Besides, by appropriately adjusting the reflection phase distribution, many other diversified functionalities can also be integrated into the meta-coupler. Our study may open up new routes for polarization-related SSP couplers, detectors, and other practical terahertz devices.

Abstract-Active terahertz beam steering by photo-generated graded index gratings in thin semiconductor films

T. P. Steinbusch, H. K. Tyagi, M.C. Schaafsma, G. Georgiou, and J. Gómez Rivas  »View Author Affiliations

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-22-22-26559

Optics Express, Vol. 22, Issue 22, pp. 26559-26571 (2014)
http://dx.doi.org/10.1364/OE.22.026559

We demonstrate active beam steering of terahertz radiation using a photo-excited thin layer of gallium arsenide. A constant gradient of phase discontinuity along the interface is introduced by an spatially inhomogeneous density of free charge carriers that are photo-generated in the GaAs with an optical pump. The optical pump has been spatially modulated to form the shape of a planar blazed grating. The phase gradient leads to an asymmetry between the +1 and −1 transmission diffracted orders of more than a factor two. Optimization of the grating structure can lead to an asymmetry of more than one order of magnitude. Similar to metasurfaces made of plasmonic antennas, the photo-generated grating is a planar structure that can achieve large beam steering efficiency. Moreover, the photo-generation of such structures provides a platform for active THz beam steering.

© 2014 Optical Society of America

Abstract-Metamaterial-based gradient index beam steerers for terahertz radiation

Jens Neu¹, René Beigang², and Marco Rahm¹

¹Department of Electrical and Computer Engineering and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany
²Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany 

http://apl.aip.org/resource/1/applab/v103/i4/p041109_s1?bypassSSO=1

We designed, fabricated, and optically characterized single and double layer metamaterial-based gradient index beam steerers for terahertz radiation. We measured a maximal deflection angle of 6°. The operation bandwidth of the beam steerers was 300 GHz around a center frequency of 1.3 THz. Within this bandwidth, the amplitude transmission was higher than 50%. Due to a thickness of only 100 μm or below, the implemented beam steerers are ideally suited for integration in compact terahertz measurement systems.

© 2013 AIP Publishing LLC