Negative frequencies in pulse propagation equations and the double analytic signal

In recent years, the topic of negative frequencies has resurfaced in optics motivated by the optical analogue of Hawking radiation. We discuss the physical meaning of negative frequencies and the conditions under which they are relevant. We review how negative frequencies are treated in current puls...

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Main Authors: Raul Aguero-Santacruz, David Bermudez
Format: Article
Language:English
Published: IOP Publishing 2023-01-01
Series:New Journal of Physics
Subjects:
Online Access:https://doi.org/10.1088/1367-2630/ad0322
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author Raul Aguero-Santacruz
David Bermudez
author_facet Raul Aguero-Santacruz
David Bermudez
author_sort Raul Aguero-Santacruz
collection DOAJ
description In recent years, the topic of negative frequencies has resurfaced in optics motivated by the optical analogue of Hawking radiation. We discuss the physical meaning of negative frequencies and the conditions under which they are relevant. We review how negative frequencies are treated in current pulse propagation models based on the electric field (EF) and the analytic signal (AS). We focus on experimentally measured signals predicted by the conservation of negative comoving frequency in the nonlinear polarization terms to advance these concepts. We propose a new formalism called the double analytic signal (DAS) which clearly separates negative frequencies from positive ones. Additionally, we reduce this new formalism to the AS to prove their equivalence. Throughout the paper, we present numerical solutions of the unidirectional pulse propagation equation to illustrate the EF, AS, and DAS formalisms and to highlight their differences.
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spelling doaj.art-bfecda462d3241aabb1fe2acd6788f862023-10-25T13:36:23ZengIOP PublishingNew Journal of Physics1367-26302023-01-01251010304510.1088/1367-2630/ad0322Negative frequencies in pulse propagation equations and the double analytic signalRaul Aguero-Santacruz0https://orcid.org/0000-0001-6897-7633David Bermudez1https://orcid.org/0000-0002-2977-0303Department of Physics, Cinvestav , A.P. 14-740, 07000 Ciudad de México, MexicoDepartment of Physics, Cinvestav , A.P. 14-740, 07000 Ciudad de México, MexicoIn recent years, the topic of negative frequencies has resurfaced in optics motivated by the optical analogue of Hawking radiation. We discuss the physical meaning of negative frequencies and the conditions under which they are relevant. We review how negative frequencies are treated in current pulse propagation models based on the electric field (EF) and the analytic signal (AS). We focus on experimentally measured signals predicted by the conservation of negative comoving frequency in the nonlinear polarization terms to advance these concepts. We propose a new formalism called the double analytic signal (DAS) which clearly separates negative frequencies from positive ones. Additionally, we reduce this new formalism to the AS to prove their equivalence. Throughout the paper, we present numerical solutions of the unidirectional pulse propagation equation to illustrate the EF, AS, and DAS formalisms and to highlight their differences.https://doi.org/10.1088/1367-2630/ad0322opticsanalogue gravitynegative frequenciespulse propagationoptical fibers
spellingShingle Raul Aguero-Santacruz
David Bermudez
Negative frequencies in pulse propagation equations and the double analytic signal
New Journal of Physics
optics
analogue gravity
negative frequencies
pulse propagation
optical fibers
title Negative frequencies in pulse propagation equations and the double analytic signal
title_full Negative frequencies in pulse propagation equations and the double analytic signal
title_fullStr Negative frequencies in pulse propagation equations and the double analytic signal
title_full_unstemmed Negative frequencies in pulse propagation equations and the double analytic signal
title_short Negative frequencies in pulse propagation equations and the double analytic signal
title_sort negative frequencies in pulse propagation equations and the double analytic signal
topic optics
analogue gravity
negative frequencies
pulse propagation
optical fibers
url https://doi.org/10.1088/1367-2630/ad0322
work_keys_str_mv AT raulaguerosantacruz negativefrequenciesinpulsepropagationequationsandthedoubleanalyticsignal
AT davidbermudez negativefrequenciesinpulsepropagationequationsandthedoubleanalyticsignal