Failure of the leaky-mode representation near the waveguide mode cutoff.
Improper eigenmodes of the planar waveguide dispersion relation, or leaky modes, are often used to represent the nonbound optical field in planar waveguides. Here we show that the improper leaky solutions give an inadequate description of the nonbound field for the important case of a waveguide just below cutoff.
Smith
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Houde-Walter
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