Self- and cross-modulation effects in a synchronously pumped optical parametric oscillator

Summary form only. Self- and cross-phase modulation effects on the pulse spectral and temporal characteristics of the synchronously pumped optical parametric oscillator (SPOPO) were investigated both theoretically and experimentally. The theoretical investigation was done by taking into account cubic nonlinearity, pulse walk-off, group velocity dispersion, quadratic broadening and higher-order nonlinear mixing such as back-conversion and optical parametric processing. Summarising the findings of the numerical analysis it should be stated that the spectral broadening of the pulses appears both due to the second- and third-order nonlinearity terms, whereas the self-phase modulation (SPM) and cross-phase modulation (XPM) terms of the third-order nonlinearity are responsible for the asymmetry of the generated spectra. Additionally, it has been found that stability of the shortened SPOPO pulses in the so-referred "giant-pulse" compression mode is also improved by self- and cross-phase modulation of the interacting pulses, and combined action of these effects leads to the formation of a train of soliton-like pulses in the synchronously pumped SPOPO.