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Title: Plasmon-enhanced terahertz emission in self-assembled quantum dots by femtosecond pulses

A scheme for terahertz (THz) generation from intraband transition in a self-assembled quantum dot (QD) molecule coupled to a metallic nanoparticle (MNP) is analyzed. The QD structure is described as a three-level atom-like system using the density matrix formalism. The MNP with spherical geometry is considered in the quasistatic approximation. A femtosecond laser pulse creates a coherent superposition of two subbands in the quantum dots and produces localized surface plasmons in the nanoparticle which act back upon the QD molecule via dipole-dipole interaction. As a result, coherent THz radiation with a frequency corresponding to the interlevel spacing can be obtained, which is strongly modified by the presence of the MNP. The peak value of the terahertz signal is analyzed as a function of nanoparticle's size, the MNP to QD distance, and the area of the applied laser field. In addition, we theoretically demonstrate that the terahertz pulse generation can be effectively controlled by making use of a train of femtosecond laser pulses. We show that by a proper choice of the parameters characterizing the pulse train a huge enhancement of the terahertz signal is obtained.
Authors:
; ; ; ;  [1] ; ;  [2] ;  [3]
  1. Facultad de Óptica y Optometría, Universidad Complutense de Madrid, C/ Arcos de Jalón 118, 28037 Madrid (Spain)
  2. Department of Physics and Astronomy, The University of Western Ontario, London N6A 3K7 (Canada)
  3. Department of Chemical and Biomolecular Engineering, University of Notre Dame, South Bend, Indiana 46556 (United States)
Publication Date:
OSTI Identifier:
22278070
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 6; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; APPROXIMATIONS; DENSITY MATRIX; DIPOLES; ENERGY-LEVEL TRANSITIONS; LASER RADIATION; MOLECULES; PARTICLE SIZE; PHOTON EMISSION; PLASMONS; PULSED IRRADIATION; QUANTUM DOTS; SPHERICAL CONFIGURATION; SURFACES; THZ RANGE