2. Linear and non-linear propagation in optical fibers

2.1 Group speed chromatic dispersion

Optical fibers are generally made mainly of silica glass, which is a dispersive material, meaning that its refractive index depends on wavelength. As a result, each spectral component of a pulse travels at a different speed from the others: this is chromatic group velocity dispersion. This phenomenon is characterized by a change in the time profile of the pulse as it leaves the propagation medium.

In an optical fiber, total chromatic dispersion depends on the intrinsic dispersion of the material (silica) and that imposed by the geometry of the waveguide (the fiber). Theoretically, to take into account the spectral dependence of the propagation constant β (ω ) in the context of light pulse propagation, a Taylor expansion around...