Controlling the Velocity of Light Pulses

  title={Controlling the Velocity of Light Pulses},
  author={Robert W. Boyd and Daniel J. Gauthier},
  pages={1074 - 1077}
Blod Blod. It is now possible to exercise a high degree of control over the velocity at which light pulses pass through material media. This velocity, known as the group velocity, can be made to be very different from the speed of light in a vacuum c. Specifically, the group velocity of light can be made much smaller than c, greater than c, or even negative. We present a survey of methods for establishing extreme values of the group velocity, concentrating especially on methods that work in… 
Slow and Fast Light in Plasma Using Optical Wave Mixing.
The ion-acoustic response in a fully ionized plasma can produce large and measurable changes in the group velocity of light, and the first experimental demonstration of slow and fast light in a plasma is shown.
Slow light from four-wave mixing on dynamic holograms
So-called ‘slow light’ is the propagation of a light pulse at a very slow speed (i.e., at a very low group velocity). The deceleration of the light pulse occurs after interacting with the medium
Slow Light in Optical Fibers
The group velocity at which light pulses propagate through a dispersive material system is very different from the vacuum speed of light c, One refers to light as being “slow” for vg c or vg <0
Taking light for a walk
Recent research on manipulating the speed of light has established the possibility of bringing down the speed of light to a value that can be challenged by a humble bullock cart. The processes that
Changing the speed of optical coherence in free space.
The concept of "coherence group velocity" is introduced which, in analogy to the group velocity of coherent pulses, is the speed of the peak of the coherence function.
Ultraslow waves on the nanoscale
How the speed of light can be controlled using designed materials and fabricated structures is reviewed and how the combination of slow light and nanotechnology gives rise to a number of effects of interest in signal processing and optoelectronic communication is shown.
5 Slow Light in Optical Fibers
The group velocity at which light pulses propagate through a dispersive material system is very different from the vacuum speed of light c, One refers to light as being “slow” for vg << c (Boyd &
Spatially structured photons that travel in free space slower than the speed of light
This work highlights that, even in free space, the invariance of the speed of light only applies to plane waves, and shows a reduction in the group velocity of photons in both a Bessel beam and photons in a focused Gaussian beam.
Controlling the velocity of ultrashort light pulses in vacuum through spatio-temporal couplings
Because of their broad spectral width, ultrashort lasers provide unique possibilities to shape light beams and control their properties, in particular through the use of spatio-temporal couplings. In
Evidence of slow-light effects from rotary drag of structured beams
Self-pumped slow light, typically observed within laser gain media, is created by an intense pump field. By observing the rotation of a structured laser beam upon transmission through a spinning ruby


The pulse velocity in a Ne absorption cell placed inside a self‐locked He–Ne (6328 A) laser has been found to exceed c, the free‐space velocity of light, by about 3 parts in 104. Conversely, the
Gain-assisted superluminal light propagation
Gain-assisted linear anomalous dispersion is used to demonstrate superluminal light propagation in atomic caesium gas and is observed to be a direct consequence of classical interference between its different frequency components in an anomalously dispersion region.
Observation of ultraslow light propagation in a ruby crystal at room temperature.
It is observed that a quantum coherence effect, coherent population oscillations, produces a very narrow spectral "hole" in the homogeneously broadened absorption profile of ruby, which leads to a large value of the group index.
The speed of information in a ‘fast-light’ optical medium
It is found that the time to detect information propagating through a fast-light medium is slightly longer than the time required to detect the same information travelling through a vacuum, even though υg in the medium vastly exceeds c.
Fundamental limit to linear one-dimensional slow light structures.
Using a new general approach to limits in optical structures that counts orthogonal waves generated by scattering, we derive an upper limit to the number of bits of delay possible in one-dimensional
Observation of Backward Pulse Propagation Through a Medium with a Negative Group Velocity
It is demonstrated that the peak of the pulse does propagate backward inside the fiber, even though the energy flow is always in the forward direction.
Slow light in saturable absorbers
In connection with the experiments recently achieved on doped crystals, biological samples, doped optical fibers and semiconductor heterostructures, we revisit the theory of the propagation of a
Light speed reduction to 17 metres per second in an ultracold atomic gas
Techniques that use quantum interference effects are being actively investigated to manipulate the optical properties of quantum systems. One such example is electromagnetically induced transparency,
Superluminal light pulse propagation via rephasing in a transparent anomalously dispersive medium.
It is shown how rephasing can produce these unusual pulse propagation phenomena when the group velocity of the pulse exceeds c and can even become negative.
Superluminal and Slow Light Propagation in a Room-Temperature Solid
It is observed that ions in mirror sites are inversely saturable and cause superluminal light propagation, whereas ions in inversion sites experience conventional saturable absorption and produce slow light.