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arXiv · 1703.00347

$CPT$-symmetric coupler with intermodal dispersion

Dmitry A. Zezyulin·Yaroslav V. Kartashov·Vladimir V. Konotop
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Abstract

A dual-core waveguide with balanced gain and loss in different arms and with intermodal coupling is considered. The system is not invariant under the conventional $PT$ symmetry but obeys $CPT$ symmetry where an additional spatial inversion $C$ corresponds to swapping the coupler arms. We show that second-order dispersion of coupling allows for unbroken $CPT$ symmetry and supports propagation of stable vector solitons along the coupler. Small-amplitude solitons are found in explicit form. The combined effect of gain-and-loss and dispersive coupling results in several interesting features which include a separation between the components in different arms, nontrivial dependence of stability of a soliton on its velocity, and the existence of more complex stationary two-hump solutions. Unusual decay dynamics of unstable solitons is discussed too.

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Dmitry A. Zezyulin, Yaroslav V. Kartashov, Vladimir V. Konotop. 2017-03-01. $CPT$-symmetric coupler with intermodal dispersion. https://doi.org/10.1364/ol.42.001273

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