Active THz Plasmonic Structures and Circuits on Flat Semiconductor Layers

Giorgos Georgiou Center for Nanophotonics, FOM Institute AMOLF, Amsterdam, Netherlands Arkabrata Bhattacharya Center for Nanophotonics, FOM Institute AMOLF, Amsterdam, Netherlands Jaime Gomez-Rivas Center for Nanophotonics, FOM Institute AMOLF, Amsterdam, Netherlands COBRA Research Institute, Eindhoven University of Technology, Eindhoven, Netherlands

Optical illumination of semiconductors leads to photoinduced doping. When the illumination is local and intense, the semiconductor transits from a dielectric to a metallic behavior at THz frequencies only at the illuminated area. We have used this concept to demonstrate experimentally the photo-excitation of THz localized surface plasmon polaritons (LSPPs) in flat semiconductor layers [1]. This is realized by a patterned optical excitation of free charge carriers in thin films of GaAs using a spatial light modulator, which enables full spatial and temporal control of resonances without the need of physically structuring the sample. This approach is also used to excite capacitively and inductively coupled LSPPs in loaded plasmonic antennas. We also propose the spatially structured photoinduced doping of semiconductors to dynamically generate plasmonic waveguides and circuits [2].

[1] G. Georgiou, H.K. Tyagi, P. Mulder, G. Bauhuis, J. Schermer and J. Gómez Rivas, Photo-generated THz antennas, Sci. Rep. 4, 3584 1-5 (2014)

[2] H.K. Tyagi and J. Gómez Rivas, Photo-generated THz plasmonic waveguides, J. Opt. 16, 094011 1-7 (2014)

georgiou@amolf.nl