Fission of narrow high power beams into multiple solitons in a second-order nonlinear slab waveguide

Summary form only given. One of the first nonlinear effects observed was the break-up of wide, high intensity, beams into filaments due to spatial noise present on the beam, known as modulational instability (MI), that generally occurs in any media with nonlinearities which lead to self-focusing. We have recently reported observation of MI near the phase-matching condition for second-harmonic generation in LiNbO/sub 3/ slab waveguides. For narrow beams, a different phenomenon can occur at lower intensities than MI, namely the fission of the beam into multiple solitons. For spatial solitons, the peak soliton intensity varies inversely with the soliton´s spatial width, so that if the input beam contains sufficient intensity to generate multiple solitons, fission occurs. Here we report experimental observation of the break-up of high intensity beams into multiple components at thresholds consistent with soliton fission.