Self-confinement of multimode optical pulse in a glass fiber

The nonlinear change of the dielectric constant (Kerr effect) in a glass fiber can be utilized to self-confine optical pulses in a multimode fiber at wavelengths longer than 1.3 microm. The range of the deviation in the group velocity Deltanu(g) of the different modes to be confined is given by Deltanu(g)(2)/nu(g)(2) </= 2( partial differentialnu(g)/ partial differentialf x f/nu(g))n(2)/n(0)|E|(2), where f and nu(g) are the frequency and the group velocity, respectively, of the mode; n(0) and n(2) (= 3 x 10(-22)m(2)/V(2)) are the linear and nonlinear indices of refraction; and E is the peak electric field averaged over the cross sections of the fiber.