D. A. B. Miller, "Fundamental limit for optical
components," J. Opt. Soc. Am. B 24, A1-A18 (2007)
http://www.opticsinfobase.org/josab/abstract.cfm?URI=josab-24-10-A1 (open access)
that there is a general limit to the performance of linear optical
components, based only on their size, shape, and dielectric constants.
The limit is otherwise independent of the design. The mathematics
applies generally to linear systems with arbitrarily strong multiple
scattering. Relevant optical structures include dielectric stacks,
photonic crystals, nanometallics, meta-materials and slow-light
structures. The limit also covers acoustic and quantum-mechanical waves,
and electromagnetic waves of any frequency. In an example
one-dimensional glass/air structure, we predict a minimum 41.7 Ám
thickness to separate pulses of 32 different frequencies near 1.55 Ám
center wavelength. Larger available dielectric constants would lead to
correspondingly shorter limits.
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