Milan Koirala
580 California St., Suite 400
San Francisco, CA, 94104
Critical states embedded in the continuum
2015, New Journal of Physics
https://doi.org/10.1088/1367-2630/17/1/013003
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Abstract
We introduce a class of critical states which are embedded in the continuum (CSC) of onedimensional optical waveguide array with one non-Hermitian defect. These states are at the verge of being fractal and have real propagation constant. They emerge at a phase transition which is driven by the imaginary refractive index of the defect 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 they evolve to exponentially localized modes. An addition of a background gain or loss can turn these localized states to bound states in the continuum.
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