Two-dimensional optical spatiotemporal solitons in quadratic media

Numerical and experimental studies of the propagation of femtosecond-duration optical pulses in quadratic nonlinear media are presented. Pulse evolution is investigated over wide ranges of initial intensity and phase mismatch between fundamental and harmonic waves, and the conditions that produce two-dimensional spatiotemporal solitons are delineated. Spatiotemporal solitons can be generated when the group velocities of the fundamental and harmonic fields are quite different, for proper choice of the phase mismatch. The factors that limit the formation of spatiotemporal solitons are discussed.