Seeded second harmonic generation is investigated by including an in-phase second-harmonic pulse.
Soliton compression from a broader input pulse with low threshold pump intensity is numerically
demonstrated in collinear quasi-phase-matching grating. Through changing the group-velocity
mismatch and pump intensity, frequency shift of another input signal pulse can be obtained with pulse
duration of few cycles, which show potential tool in ultrafast pulse application and is useful for
generation of shorter pulses with clean temporal profiles.