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Title: Coherent all-optical switching by resonant quantum-dot distributions in photonic band-gap waveguides

Abstract

We study the detailed propagative characteristics of optical pulses in photonic band-gap (PBG) waveguides, coupled near resonantly to inhomogeneously broadened distributions of quantum dots. The line centers of the quantum-dot (QD) distributions are placed near a sharp discontinuity in the local electromagnetic density of states. Using finite-difference time-domain (FDTD) simulations of optical pulse dynamics and independent QD susceptibilities associated with resonance fluorescence, we demonstrate subpicosecond switching from pulse absorption to pulse amplification using steady-state optical holding and gate fields with power levels on the order of 1 milliwatt. In the case of collective response of QDs within the periodic dielectric microstructure, the gate power level is reduced to 200 microwatt for room temperature operation. In principle, this enables 200 Gbits per second optical information processing at wavelengths near 1.5 microns in various wavelength channels. The allowed pulse bandwidth in a given waveguide channel exceeds 0.5 THz allowing switching of subpicosecond laser pulses without pulse distortion. The switching contrast from absorption to gain is governed by the QD oscillator strength and dipole dephasing time scale. We consider dephasing time scales ranging from nanoseconds (low-temperature operation) to one picosecond (room-temperature operation). This all-optical transistor action is based on simple Markovian models ofmore » single-dot and collective-dot inversion and switching by coherent resonant pumping near the photon density of states discontinuity. The structured electromagnetic vacuum is provided by two-mode waveguide architectures in which one waveguide mode has a cutoff that occurs, with very large Purcell factor, near the QDs resonance, while the other waveguide mode exhibits nearly linear dispersion for fast optical propagation and modulation. Unlike optical switching based on Kerr nonlinearities in an optical cavity resonator, switching power levels and switching speeds for our QD device are not inversely proportional to cavity quality factors.« less

Authors:
;  [1]
  1. Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario, M5S-1A7 (Canada)
Publication Date:
OSTI Identifier:
21140707
Resource Type:
Journal Article
Journal Name:
Physical Review. A
Additional Journal Information:
Journal Volume: 76; Journal Issue: 6; Other Information: DOI: 10.1103/PhysRevA.76.063814; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1050-2947
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION; CAVITY RESONATORS; CRYSTALS; DIPOLES; LASER CAVITIES; LASER RADIATION; MARKOV PROCESS; NONLINEAR PROBLEMS; OSCILLATOR STRENGTHS; PERIODICITY; PHOTONS; QUALITY FACTOR; QUANTUM DOTS; RESONANCE; RESONANCE FLUORESCENCE; SIMULATION; STEADY-STATE CONDITIONS; TEMPERATURE RANGE 0273-0400 K; VELOCITY; WAVEGUIDES

Citation Formats

Vujic, Dragan, and John, Sajeev. Coherent all-optical switching by resonant quantum-dot distributions in photonic band-gap waveguides. United States: N. p., 2007. Web. doi:10.1103/PHYSREVA.76.063814.
Vujic, Dragan, & John, Sajeev. Coherent all-optical switching by resonant quantum-dot distributions in photonic band-gap waveguides. United States. doi:10.1103/PHYSREVA.76.063814.
Vujic, Dragan, and John, Sajeev. Sat . "Coherent all-optical switching by resonant quantum-dot distributions in photonic band-gap waveguides". United States. doi:10.1103/PHYSREVA.76.063814.
@article{osti_21140707,
title = {Coherent all-optical switching by resonant quantum-dot distributions in photonic band-gap waveguides},
author = {Vujic, Dragan and John, Sajeev},
abstractNote = {We study the detailed propagative characteristics of optical pulses in photonic band-gap (PBG) waveguides, coupled near resonantly to inhomogeneously broadened distributions of quantum dots. The line centers of the quantum-dot (QD) distributions are placed near a sharp discontinuity in the local electromagnetic density of states. Using finite-difference time-domain (FDTD) simulations of optical pulse dynamics and independent QD susceptibilities associated with resonance fluorescence, we demonstrate subpicosecond switching from pulse absorption to pulse amplification using steady-state optical holding and gate fields with power levels on the order of 1 milliwatt. In the case of collective response of QDs within the periodic dielectric microstructure, the gate power level is reduced to 200 microwatt for room temperature operation. In principle, this enables 200 Gbits per second optical information processing at wavelengths near 1.5 microns in various wavelength channels. The allowed pulse bandwidth in a given waveguide channel exceeds 0.5 THz allowing switching of subpicosecond laser pulses without pulse distortion. The switching contrast from absorption to gain is governed by the QD oscillator strength and dipole dephasing time scale. We consider dephasing time scales ranging from nanoseconds (low-temperature operation) to one picosecond (room-temperature operation). This all-optical transistor action is based on simple Markovian models of single-dot and collective-dot inversion and switching by coherent resonant pumping near the photon density of states discontinuity. The structured electromagnetic vacuum is provided by two-mode waveguide architectures in which one waveguide mode has a cutoff that occurs, with very large Purcell factor, near the QDs resonance, while the other waveguide mode exhibits nearly linear dispersion for fast optical propagation and modulation. Unlike optical switching based on Kerr nonlinearities in an optical cavity resonator, switching power levels and switching speeds for our QD device are not inversely proportional to cavity quality factors.},
doi = {10.1103/PHYSREVA.76.063814},
journal = {Physical Review. A},
issn = {1050-2947},
number = 6,
volume = 76,
place = {United States},
year = {2007},
month = {12}
}