Dispersion map induced energy transfer between solitons in optical fibres

We propose an experimental setup to study collision-induced soliton amplification. In an optical fibre with anomalous dispersion ($\beta_2 < 0$), we replace a small region of the fibre with a normal dispersion fibre ($\beta_2 > 0$). We show that solitons colliding in this region are able to exchange energy. Depending on the relative phase of the soliton pair, we find that the energy transfer can lead to an energy gain in excess of $20\%$ for each collision. A sequence of such events can be used to enhance the energy gain even further, allowing the possibility of considerable soliton amplification. This energy transfer does not require a third order dispersion or Raman term.