Photonic crystals are assigned an effective refractive index defined by their dispersion relation. This can predict their refractive properties consistent with Snell's law, but might not predict their dynamic properties according to the Fresnel formulae.
© 2005 Optical Society of America
B. T. Schwartz and R. Piestun, "How Effective is the Effective Refractive Index?," in Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science and Photonic Applications Systems Technologies, Technical Digest (CD) (Optical Society of America, 2005), paper QFA5.
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