Abstract

Solitons due to parametric mixing in quadratic (χ⁽²⁾) media constitute an active area of research. In few years, spatial solitons,¹ filamentation,² temporal trapping,³ and spatio-temporal effects⁴ have been observed. The cascading limit,⁵ i.e., an effective self-focusing Kerr-like action occuring for large positive mismatches Δk = 2k(ω) - k(2ω) is often invoked to understand trapping in second-harmonic generation (SH-G). The self-focusing nature of χ⁽²⁾ mixing for large Δk > 0 is then taken for granted, irrespective of frequency (ω or 2ω) and launching conditions (SHG versus downconversion or optical parametric amplification, OPA).⁶

© 2001 Optical Society of America