Line-by-line pulse shaping with spectral resolution below 890 MHz.

Line-by-line pulse shaping is demonstrated on a 890 MHz repetition rate mode-locked titanium sapphire laser. The high resolution pulse shaper is based on a virtual imaged phased array (VIPA) with a free spectral range of 25 GHz. For our implementation, the mask repeats every VIPA free spectral range, which corresponds to every 28 comb lines. Individual frequency modes from the laser are also resolved using the same VIPA paired with a diffraction grating to achieve a resolution of 357 MHz. Several output waveforms are compared with simulation to understand differences with the ideal case.