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Title: Highly efficient terahertz wave modulators by photo-excitation of organics/silicon bilayers

Using hybrid bilayer systems comprising a molecular organic semiconductor and silicon, we achieve optically controllable active terahertz (THz) modulators that exhibit extremely high modulation efficiencies. A modulation efficiency of 98% is achieved from thermally annealed C{sub 60}/silicon bilayers, due to the rapid photo-induced electron transfer from the excited states of the silicon onto the C{sub 60} layer. Furthermore, we demonstrate the broadband modulation of THz waves. The cut-off condition of the system that is determined by the formation of efficient charge separation by the photo-excitation is highly variable, changing the system from insulating to metallic. The phenomenon enables an extremely high modulation bandwidth and rates of electromagnetic waves of interest. The realization of near-perfect modulation efficiency in THz frequencies opens up the possibilities of utilizing active modulators for THz spectroscopy and communications.
Authors:
; ;  [1] ;  [2] ;  [3] ;  [1] ;  [4] ;  [5]
  1. Advanced Photonics Research Institute, GIST, Gwangju 500-712 (Korea, Republic of)
  2. Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Seoul 136-791 (Korea, Republic of)
  3. Department of Physics, Sogang University, Seoul 121-742 (Korea, Republic of)
  4. (Korea, Republic of)
  5. Department of Physics, Chonnam National University, Gwangju 500-757 (Korea, Republic of)
Publication Date:
OSTI Identifier:
22303930
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 1; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANNEALING; EFFICIENCY; ELECTROMAGNETIC RADIATION; ELECTRON TRANSFER; EXCITATION; EXCITED STATES; FULLERENES; HYBRID SYSTEMS; LAYERS; MODULATION; ORGANIC SEMICONDUCTORS; SILICON; SPECTROSCOPY; THZ RANGE