Dispersion varying fibers for optical signal processing

The single mode fibers with chromatic dispersion varying along the length are attracting a considerable attention due to their value for optical soliton processing and applications in stable sources of ultra short optical pulses. In particular, dispersion decreasing fibers (DDF) have been recognized to be useful for high-quality soliton pulse compression and stable against pump noise continuum generation. The fibers with varying along length dispersion can have a lot of application in optical signal processing. The method to produce fibers varying along the length from standard preform had been developed. It is possible to draw fibers with a necessary length dependence on the diameter with high accuracy. During the drawing process information about the current diameter is processed by digital control unit and compared with a calculated value. The dispersion deviation from the prearranged value is less than 0.1ps/nm/km. High-quality pulse compression has been obtained in DDF. The compression factor is determined by the ratio of input to output dispersion and typically limited to about 20. Using DDF with optimum dispersion profile it is possible to generate pedestal-free pulses of less than 50fs duration. In addition, a new DDF design allows to increase the SBS threshold by 7dB over the conventional nonlinear fibers.