Asymmetric pendulum effect and transparency change of PT-symmetric photonic crystals under dynamical Bragg diffraction beyond the paraxial approximationстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 16 октября 2018 г.
Аннотация:Light propagating in PT-symmetric photonic crystals (PhCs) under Bragg diffraction in the Laue geometry has been studied theoretically using the spectral method. The PT-symmetric solutions describing propagating modes have been found in the PhCs with gain and loss beyond paraxial approximation. We described the pendulum effect—the periodical spatial localization of the total field intensity in a PhC—near the PT-symmetry-breaking point. It is shown that, due to PT-symmetric properties of the medium, an asymmetric change in the amplitudes of the diffracted waves in PhCs is observed when the sign of the Bragg incidence angle is changed from positive to negative. Thus, the intensity of a spatially periodic field in a medium radically alters under the pendulum effect. Moreover, when the sign of the Bragg incidence angle changes, a PhC of a certain thickness is turned from an absorbing structure into an amplifying one, also a PhC of any thickness evolves from completely transparent into amplifying in the vicinity of the PT-symmetry-breaking point. Under a small change of the imaginary part of permittivity, the light switching from a transmitted wave into a gain or loss diffracted wave is possible in a diffraction-thick PhC.