Dispersion of nonlinearity in subwavelength waveguides: derivation of pulse propagation equation and frequency conversion effects

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Abstract

Description of pulse propagation in waveguides with subwavelength features and high refractive index contrasts requires an accurate account of the dispersion of nonlinearity due to the considerable mode profile variation with the wavelength. The corresponding model derived from asymptotic expansion of Maxwell equations contains a complicated network of interactions between different harmonics of the pulse, and therefore is not convenient for analysis. We demonstrate that this model can be reduced to the generalized nonlinear Schrödinger-type pulse propagation equation under the assumption of factorization of the four-frequency dependence of nonlinear coefficients. We analyze two different semiconductor waveguide geometries and find that the factorization works reasonably well within large wavelength windows. This allows us to utilize the pulse propagation equation for the description of a broadband signal evolution. We study the mechanism of modulational instability induced by the dispersion of nonlinearity and find that the power threshold predicted by the simple model with three interacting harmonics is effectively removed when using pulses, while the efficiency of this process grows for shorter pulse durations. Also, we identify the effects of geometrical and material dispersion of nonlinearity on spectral broadening of short pulses in semiconductor waveguides.
LanguageEnglish
Pages812-820
Number of pages9
JournalJournal of the Optical Society of America B-Optical Physics
Volume30
Issue number4
Early online date6 Mar 2013
DOIs
StatusPublished - 2013

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frequency converters
derivation
nonlinearity
waveguides
propagation
pulses
factorization
harmonics
wavelengths
Maxwell equation
pulse duration
refractivity
broadband
expansion
thresholds
coefficients
profiles
geometry
interactions

Cite this

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title = "Dispersion of nonlinearity in subwavelength waveguides: derivation of pulse propagation equation and frequency conversion effects",
abstract = "Description of pulse propagation in waveguides with subwavelength features and high refractive index contrasts requires an accurate account of the dispersion of nonlinearity due to the considerable mode profile variation with the wavelength. The corresponding model derived from asymptotic expansion of Maxwell equations contains a complicated network of interactions between different harmonics of the pulse, and therefore is not convenient for analysis. We demonstrate that this model can be reduced to the generalized nonlinear Schr{\"o}dinger-type pulse propagation equation under the assumption of factorization of the four-frequency dependence of nonlinear coefficients. We analyze two different semiconductor waveguide geometries and find that the factorization works reasonably well within large wavelength windows. This allows us to utilize the pulse propagation equation for the description of a broadband signal evolution. We study the mechanism of modulational instability induced by the dispersion of nonlinearity and find that the power threshold predicted by the simple model with three interacting harmonics is effectively removed when using pulses, while the efficiency of this process grows for shorter pulse durations. Also, we identify the effects of geometrical and material dispersion of nonlinearity on spectral broadening of short pulses in semiconductor waveguides.",
author = "Xuesong Zhao and Gorbach, {Andriy V} and Skryabin, {Dmitry V}",
year = "2013",
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TY - JOUR

T1 - Dispersion of nonlinearity in subwavelength waveguides: derivation of pulse propagation equation and frequency conversion effects

AU - Zhao, Xuesong

AU - Gorbach, Andriy V

AU - Skryabin, Dmitry V

PY - 2013

Y1 - 2013

N2 - Description of pulse propagation in waveguides with subwavelength features and high refractive index contrasts requires an accurate account of the dispersion of nonlinearity due to the considerable mode profile variation with the wavelength. The corresponding model derived from asymptotic expansion of Maxwell equations contains a complicated network of interactions between different harmonics of the pulse, and therefore is not convenient for analysis. We demonstrate that this model can be reduced to the generalized nonlinear Schrödinger-type pulse propagation equation under the assumption of factorization of the four-frequency dependence of nonlinear coefficients. We analyze two different semiconductor waveguide geometries and find that the factorization works reasonably well within large wavelength windows. This allows us to utilize the pulse propagation equation for the description of a broadband signal evolution. We study the mechanism of modulational instability induced by the dispersion of nonlinearity and find that the power threshold predicted by the simple model with three interacting harmonics is effectively removed when using pulses, while the efficiency of this process grows for shorter pulse durations. Also, we identify the effects of geometrical and material dispersion of nonlinearity on spectral broadening of short pulses in semiconductor waveguides.

AB - Description of pulse propagation in waveguides with subwavelength features and high refractive index contrasts requires an accurate account of the dispersion of nonlinearity due to the considerable mode profile variation with the wavelength. The corresponding model derived from asymptotic expansion of Maxwell equations contains a complicated network of interactions between different harmonics of the pulse, and therefore is not convenient for analysis. We demonstrate that this model can be reduced to the generalized nonlinear Schrödinger-type pulse propagation equation under the assumption of factorization of the four-frequency dependence of nonlinear coefficients. We analyze two different semiconductor waveguide geometries and find that the factorization works reasonably well within large wavelength windows. This allows us to utilize the pulse propagation equation for the description of a broadband signal evolution. We study the mechanism of modulational instability induced by the dispersion of nonlinearity and find that the power threshold predicted by the simple model with three interacting harmonics is effectively removed when using pulses, while the efficiency of this process grows for shorter pulse durations. Also, we identify the effects of geometrical and material dispersion of nonlinearity on spectral broadening of short pulses in semiconductor waveguides.

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