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Updated: Aug 11, 2026

Fabrication And Characterization Of Photonic Crystal Slow Light Waveguides And Cavities
Published on: November 30, 2012
Propagation speed of evanescent modes
Barbero1, Hernandez-Figueroa, Recami
1DMO, FEEC, Universidade Estadual de Campinas, Campinas, SP, Brazil and TET, CTC, Universidade Federal Fluminense, RJ, Brazil.
Abstract:
The group velocity of evanescent waves (in undersized waveguides, for instance) was theoretically predicted, and has been experimentally verified, to be superluminal (v(g)>c). By contrast, it is known that the precursor speed in vacuum cannot be larger than c. In this paper, by computer simulations based on Maxwell equations only, we show the existence of both phenomena. In other words, we verify the actual possibility of superluminal group velocities, without violating the so-called (naive) Einstein causality.
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