Conjugate wavefront generation (CWG) in GaP monocrystals using picosecond light pulses at 1.06 μm wavelength, i.e. in the transparent range of the material, is demonstrated. The read-out beam was obtained from the back cleaved surface of the monocrystal, or from an external mirror in a DFWM configuration. We found the threshold of CWG at ∼ 1 J cm 2 . The increase of signal energy with laser energy is limited, by damage of the surface of the semiconductor material, at 2–3 J cm 2 . The recording mechanism is assumed to be thermal modulation of the refractive index. CWG in Si on GaP monocrystals, at the same wavelength, is also studied. The threshold of CWG was obtained at ∼ 0.1 J cm 2 , set by the detection noise. The range of CWG was uprated by the recording of stationary holograms, at 0.4–0.5 J cm 2 , due to the local polycrystallization of the amorphous material in solid phase. Thus, CWG can be used for the characterization of the early stages of crystallization of amorphous layers.