Both Fresnel diffraction and propagation in second order dispersive transmission lines are expressed by Fresnel integrals and a unified approach of these domains can be developed on the basis of this formal analogy. Spatial curvatures of spherical emitters and receivers, as used in the metaxial theory of diffraction, and temporal chirp functions are shown to be equivalent. As a consequence, results proved in diffraction theory can be transposed to transmission lines; classical formulae that hold true for Gaussian beams have their exact counterparts that apply to Gaussian wave packet propagation in optical fibers. Applications to dispersion compensation in optical communication systems are explicitely described.