Transient energy transfer on the femtosecond timescale in lithium niobate

Amplification of a weak signal pulse on expense of a strong pump pulse is a commonly used phenomenon in nonlinear optics. When applying a non-collinear interaction geometry of two ultrashort laser pulses an interference pattern can be observed that might give rise to a grating inside a nonlinear optical crystal. As recently reported, even pulses with different central frequencies can form an interference pattern with sufficient modulation that is favourable to be the origin of the amplification of a weak signal pulse [1]. We aim to reveal the process of amplification of a weak signal pulse in the context of transient energy transfer at a self-recorded grating in the frequency degenerated case of two femtosecond laser pulses.