Single shot method for real time femtosecond pulse field reconstruction

We have experimentally demonstrated a new configuration of Single-Shot SPIRIT was validated during the characterization of nearly gaussian femtosecond pulses exiting of a Ti:Sapphire laser source, which delivers pulses at 75 MHz repetition rate at 830 nm. This technique permits to have fast and direct access to phase and amplitude of short optical pulses. The extension to low repetition rate amplified femtosecond system is under way. A detectivity threshold in the range of 100 nanojoules has been estimated in the case of single femtosecond pulse measurement. The numerical model will enable us to foresee the limitation of the technique. In the output plane of the setup, this gate pulse is spatially broadened by a cylindrical lens. The remaining fraction of the initial pulse enters a Mach-Zehnder interferometer which will generate a pair of twin pulses. After dispersion by a diffraction grating, the twin spectra are displayed in the output.