Ultrashort vortex laser pulses diagnostic based on multi-pinhole interferometer

In this paper we report on a simple method for characterizing ultrashort vortex laser pulses generated from Erbium-doped fiber laser. The single-mode fiber oscillator can produce mode-locked pluses with duration of 316 fs around 1550 nm. By passing linearly polarized TEM00 Gaussian mode-locked pulses through vortex retarders, ultrashort vortex laser pulses are created, and the topological charge numbers of the vortex beams are characterized through far field multi-pinhole interferometer. The experiment results agree well with simulation. This diagnostic method will benefit vortex beam generation and advance its application for ultrafast science.