Research of influence of parameters of ultrashort pulse on intensity of precursors

Simulation of short optical pulses in the planar waveguide of silica glass showed that in the case of initial rectangular pulse with a carrier wavelength $\lambda_0=532$ nm (away from resonance) and pulse duration equal $0,5\lambda_0(n+0,5)$, $n$ — an integer, precursors intensity increases by about 2 at a distance of tens of microns away from the origin. Although intensity of precursors is about $1\%$ compared with the intensity of the main pulse. But if you choose the length of the pulse wave at the nearest resonance ($\lambda_0=120$ nm), the intensity of the precursors may exceed the intensity of the main pulse of 4 times.