Group velocity dispersion

In optics, group velocity dispersion (GVD) is a characteristic of a dispersive medium, used most often to determine how the medium will affect the duration of an optical pulse traveling through it. Formally, GVD is defined as the derivative of the inverse of group velocity of light in a material with respect to angular frequency,

where ${\displaystyle \omega }$ and ${\displaystyle \omega _{0}}$ are angular frequencies, and the group velocity ${\displaystyle v_{g}(\omega )}$ is defined as ${\displaystyle v_{g}(\omega )\equiv \partial \omega /\partial k}$. The units of group velocity dispersion are [time]²/[distance], often expressed in fs²/mm.

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