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.
Formula:
(GVD)ω0 = (∂/∂×ω) × (1 / vg(ω))
where,ω - angular frequency
vg(ω) - group velocity