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Updated: Aug 11, 2026
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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.
Summary
Superluminal group velocities exceeding the speed of light (c) are possible in evanescent waves. Computer simulations confirm this phenomenon without violating Einstein causality, reconciling theoretical predictions with experimental observations.
Area of Science:
- Physics
- Electromagnetism
- Wave Propagation
Background:
- Evanescent waves in undersized waveguides exhibit theoretically predicted superluminal group velocities (v(g)>c).
- The precursor speed in vacuum is known to be limited by the speed of light (c).
Purpose of the Study:
- To investigate the coexistence of superluminal group velocities and the precursor speed limit.
- To verify the possibility of superluminal group velocities using computer simulations based solely on Maxwell equations.
- To demonstrate that superluminal group velocities do not violate Einstein causality.
Main Methods:
- Computer simulations based on Maxwell equations.
- Analysis of wave propagation phenomena.
Main Results:
- Demonstrated the existence of superluminal group velocities for evanescent waves.
- Confirmed that these superluminal velocities do not violate Einstein causality.
- Reconciled theoretical predictions and experimental verifications of superluminal group velocities.
Conclusions:
- Superluminal group velocities are achievable in specific wave phenomena like evanescent waves.
- Maxwell's equations support the occurrence of superluminal group velocities without causal paradoxes.
- The study validates the theoretical and experimental findings on superluminal group velocities.
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