Interference and holography with femtosecond laser pulses of different colours.

Interferometry and holography are two domains that are based on observation and recording of interference fringes from two light beams. While the aim of the first technique is to reveal and map the phase difference of two wave fronts, the main task of the second technique is to reconstruct one of the two recording waves via diffraction of the other wave from the recorded fringe pattern (hologram). To create fringes, mutually coherent waves from the same laser are commonly used. It is shown here that fringes can be observed and holograms can be recorded with ultrashort, sub-picosecond pulses even of different colour, generated in our experiment with two parametric amplifiers seeded, both by the same mode-locked Ti-sapphire laser. The appearance of permanent and transient gratings is confirmed by recording of an image-bearing hologram, by observation of two-beam coupling gain in a pump-probe experiment and by frequency conversion in Raman-Nath self-diffraction from a moving grating.