Soliton order
= Soliton order
{title2=$N_s^2=L_D/L_{\rm NL}$}
A dimensionless comparison of dispersion and <self-phase modulation> scales. For the focusing cubic fibre equation with a sech input, $N_s=1$ gives a <fundamental temporal bright soliton>, and integer $N_s>1$ gives an ideal <higher-order temporal soliton>. It is a scale parameter for an arbitrary initial pulse, not a theorem that the pulse contains exactly that many separated <solitons>.