DARK SOLITON TRAINS FORMED BY VISIBLE PULSE COLLISIONS IN OPTICAL FIBERS

It is shown that, through the nonlinear collision of two visible pulses copropagating in an optical fiber, a high-frequency train of dark pulses form, which are well described by the analytic dark soliton solution. Numerical solutions of the nonlinear Schroedinger equation show that the solitons form without secondary pulses and their pulsewidths adiabatically broaden in concert with the slowly decreasing intensity of the background pulse upon which they are situated. For equal input pulse intensities it is shown that the dark pulses asymptotically approach the fundamental dark soliton.