Quadratic soliton collisions.

The details of two soliton collision processes were investigated in detail in a 1 cm long periodically poled KTP crystal for the case when the solitons were excited by inputting only the fundamental beam. The effects on the collision outcomes of the distance of the collision into the sample, collision angle and phase mismatch were measured for different relative phases between the input beams. At small angles (around 0.4 degrees ) fusion, repulsion and energy transfer processes were observed, while at the collision angles approaching 3.2 degrees the two output soliton beams were essentially unaffected by the interaction. The phase mismatch was varied from 3.5 to -1.5pi for the 0.4 degrees collision angle case. The output solitons separation at pi input phase difference showed strongly asymmetric behavior with phase mismatch. In general, the measurements indicate a decrease in the interaction strength with increasing phase mismatch. All collision processes were performed in the vicinity of a non-critical phase matching.