Steinbusch, T.P., Tyagi, H.K., Schaafsma, M.C., Georgiou, G. and Gómez Rivas, J. (2014) Active terahertz beam steering by photo-generated graded index gratings in thin semiconductor films. Optics Express, 22(22), pp. 26559-26571. (doi: 10.1364/OE.22.026559) (PMID:25401807)
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Abstract
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.
| Item Type: | Articles |
|---|---|
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Georgiou, Dr Giorgos |
| Authors: | Steinbusch, T.P., Tyagi, H.K., Schaafsma, M.C., Georgiou, G., and Gómez Rivas, J. |
| College/School: | College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering |
| Journal Name: | Optics Express |
| Publisher: | Optical Society of America |
| ISSN: | 1094-4087 |
| ISSN (Online): | 1094-4087 |
| Published Online: | 20 October 2014 |
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