Publication

Slow, superluminal and negative group velocity in optical fibres using stimulated Brillouin scattering

Luc Thévenaz
2005
Conference Papers

Abstract

Active control of the group velocity in optical fibres is demonstrated, allowing long delays, faster-than-light propagation and even negative velocity, for which the peak of a pulse exits the fibre before entering the input end

Official source

https://infoscience.epfl.ch/entities/publication/e811c2ef-79db-4641-91d0-0aa3ef58e1c7

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Luc Thévenaz
2005
Conference Papers

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/e811c2ef-79db-4641-91d0-0aa3ef58e1c7

About this result

Related concepts (19)

Group velocity

The group velocity of a wave is the velocity with which the overall envelope shape of the wave's amplitudes—known as the modulation or envelope of the wave—propagates through space. For example, if a stone is thrown into the middle of a very still pond, a circular pattern of waves with a quiescent center appears in the water, also known as a capillary wave. The expanding ring of waves is the wave group or wave packet, within which one can discern individual waves that travel faster than the group as a whole.

Phase velocity

The phase velocity of a wave is the rate at which the wave propagates in any medium. This is the velocity at which the phase of any one frequency component of the wave travels. For such a component, any given phase of the wave (for example, the crest) will appear to travel at the phase velocity. The phase velocity is given in terms of the wavelength λ (lambda) and time period T as Equivalently, in terms of the wave's angular frequency ω, which specifies angular change per unit of time, and wavenumber (or angular wave number) k, which represent the angular change per unit of space, To gain some basic intuition for this equation, we consider a propagating (cosine) wave A cos(kx − ωt).

Angular velocity

In physics, angular velocity (symbol ω, sometimes Ω), also known as angular frequency vector, is a pseudovector representation of how the angular position or orientation of an object changes with time, i.e. how quickly an object rotates (spins or revolves) around an axis of rotation and how fast the axis itself changes direction. The magnitude of the pseudovector, , represents the angular speed (or angular frequency), the rate at which the object rotates (spins or revolves).

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