Observation of the formation of dark-soliton trains in optical fibers

We present observations that demonstrate a technique for the generation of trains of dark solitons. The technique consists of the nonlinear copropagation of two delayed visible pulses in a long optical fiber. Single-shot streak-camera temporal images depict the formation of trains of dark solitons with picosecond widths. Single-shot spectra are also observed and depict ringing around spectral holes, which is characteristic of dark solitons on a chirped background pulse. Good agreement is found between theory and both temporal and spectral measurements.