Transverse instability of spatiotemporal solitons

Summary form only given. Spatiotemporal solitons (STS) result from the simultaneous balance of diffraction and group-velocity dispersion (GVD) by self-focussing and nonlinear phase-modulation, respectively. Liu et al. (1999) reported the formation of pulses that overcome diffraction in one transverse spatial dimension as well as group-velocity dispersion to reach stable or periodically-stable beam size and pulse duration; diffraction occurs in the remaining transverse spatial dimension. These pulses are referred to as 2D STS, to distinguish them from 3D STS, which are localized in all dimensions. In quadratic media, the soliton consists of fundamental and harmonic fields, coupled and mutually trapped by the nonlinear interaction. We report a study of the effects that limit stable STS propagation. The instabilities of waves propagating in nonlinear systems can lead to dramatic physical effects. In particular, we focus on the first observation of transverse instability (or modulation instability) of STS. Experiments were performed with a 25 mm crystal of barium metaborate.