English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We suggest an inverse dispersion method for calculating photonic band diagramfor materials with arbitrary frequency-dependent dielectric functions. Themethod is able to calculate the complex wave vector for a given frequency bysolving the eigenvalue problem with a non-Hermitian operator. The analogy with$\cal{PT}$-symmetric Hamiltonians reveals that the operator corresponds to themomentum as a physical quantity and the singularities at the band edges arerelated to the branch points and responses for the features on the band edges.The method is realized using plane wave expansion technique for two-dimensionalperiodical structure in the case of TE- and TM-polarization. We illustrate theapplicability of the method by calculation of the photonic band diagrams of aninfinite two-dimension square lattice composed of dielectric cylinders usingthe measured frequency dependent dielectric functions of different materials(amorphous hydrogenated carbon, silicon, and chalcogenide glass). We show thatthe method allows to distinguish unambiguously between Bragg and Mie gaps inthe spectra.

Inverse dispersion method for calculation of complex photonic band diagram and $\cal{PT}$-symmetry