We introduce a class of critical states which are embedded in the continuum (CSC) of a one-dimensional optical waveguide array with one non-Hermitian defect. These states are on the verge of being fractal and have real propagation constants. They emerge at a phase transition which is driven by the imaginary refractive index of the defective waveguide and it is accompanied by a mode segregation which reveals analogies with the Dicke super-radiance. Below this point the states are extended while above it they evolve to exponentially localized modes. An addition of a background gain or loss can turn these localized states into bound states in the continuum.
M. Koirala et al., "Critical States Embedded in the Continuum," New Journal of Physics, vol. 17, Institute of Physics Publishing, Jan 2015.
The definitive version is available at https://doi.org/10.1088/1367-2630/17/1/013003
Keywords and Phrases
Refractive Index; Waveguides; Bound State; Critical State; Hermitians; Localization; Localized Modes; Localized State; Optical Waveguide Arrays; Real Propagation; Optical Waveguides
International Standard Serial Number (ISSN)
Article - Journal
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01 Jan 2015