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Group velocity

About: Group velocity is a research topic. Over the lifetime, 10051 publications have been published within this topic receiving 204007 citations. The topic is also known as: group speed.


Papers
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Journal ArticleDOI
TL;DR: The first observation of the modulational instability of light waves in dielectric material using a neodymium-doped yttrium aluminum garnet laser operated at 1.319 \ensuremath{\mu}m and single-mode optical fibers with anomalous group-velocity dispersion is reported.
Abstract: We report the first observation of the modulational instability of light waves in dielectric material using a neodymium-doped yttrium aluminum garnet laser operated at 1.319 \ensuremath{\mu}m and single-mode optical fibers with anomalous group-velocity dispersion. The observed results are in good agreement with the theoretical predictions. The relationship between the modulation instability and parametric four-wave mixing and the interplay with stimulated Raman and Brillouin scatterings are also presented.

712 citations

Journal ArticleDOI
TL;DR: In this paper, a model for the response of surface waves in the gravity-capillary equilibrium region of the spectrum is proposed on the basis of a local (in wavenumber) balance between wind input and dissipation.
Abstract: To provide theoretical basis for the connection between observed radar scattering and wind-generated waves, a model for the response of surface waves in the gravity-capillary equilibrium region of the spectrum is proposed on the basis of a local (in wavenumber) balance between wind input and dissipation. The wind input function was constructed on the basis of laboratory observations of short-wave growth, while the dissipation function was developed from ideas of viscous dissipation and wave breaking in response to local accelerations and modified by kinematic effects of phase and group velocity differences. The model was exercised at L, C, X, and Ka bands to demonstrate the differences in wind speed and water temperature sensitivity.

690 citations

Journal ArticleDOI
TL;DR: 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.
Abstract: We have observed slow light propagation with a group velocity as low as $57.5\ifmmode\pm\else\textpm\fi{}0.5\text{ }\mathrm{m}/\mathrm{s}$ at room temperature in a ruby crystal. A quantum coherence effect, coherent population oscillations, produces a very narrow spectral ``hole'' in the homogeneously broadened absorption profile of ruby. The resulting rapid spectral variation of the refractive index leads to a large value of the group index. We observe slow light propagation both for Gaussian-shaped light pulses and for amplitude modulated optical beams in a system that is much simpler than those previously used for generating slow light.

651 citations

Journal ArticleDOI
TL;DR: In this article, slow group velocities of light, which are readily achievable in photonic-crystal systems, can dramatically increase the induced phase shifts caused by small changes in the index of refraction.
Abstract: We demonstrate how slow group velocities of light, which are readily achievable in photonic-crystal systems, can dramatically increase the induced phase shifts caused by small changes in the index of refraction. Such increased phase sensitivity may be used to decrease the sizes of many devices, including switches, routers, all-optical logical gates, wavelength converters, and others. At the same time a low group velocity greatly decreases the power requirements needed to operate these devices. We show how these advantages can be used to design switches smaller than 20 µm×200 µm in size by using readily available materials and at modest levels of power. With this approach, one could have ∼105 such devices on a surface that is 2 cm×2 cm, making it an important step towards large-scale all-optical integration.

645 citations

Journal ArticleDOI
TL;DR: In this paper, the frequency and amplification rates for a disturbance growing with respect to time are compared with those of a spatially growing wave having the same wave number, and it is shown that the frequencies are equal to a high order of approximation.
Abstract: The frequency and amplification rates for a disturbance growing with respect to time are compared with those of a spatially-growing wave having the same wave-number. For small rates of amplification it is shown that the frequencies are equal to a high order of approximation, and that the spatial growth is related to the time growth by the group velocity.

632 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202364
2022133
2021198
2020219
2019246
2018233