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

T.P. Steinbusch, H.K. Tyagi, M.C. Schaafsma, Giorgos Georgiou, J. Gomez Rivas

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30 Citaten (Scopus)
239 Downloads (Pure)

Samenvatting

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.
Originele taal-2Engels
Pagina's (van-tot)26559-26571
Aantal pagina's12
TijdschriftOptics Express
Volume22
Nummer van het tijdschrift22
DOI's
StatusGepubliceerd - 2014

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