Abstract

After the advent of methods like FROG and SPIDER, temporal characterization of ultrashort pulses can nowadays be considered a mature technology. These methods deliver reliable access to the pulse profile and the phase for a vast range of femtosecond pulses. However, when it comes to extremely broadband few-cycle pulses, even these methods increasingly face challenges. All FROG variants discussed to date either suffer from a beam smearing distortion due to a non-collinear geometry or from the availability of suitably thin nonlinear crystals. At first sight, SPIDER appears more robust against these limitations, but nevertheless also encounters a hidden limitation due to the available phase-matching bandwidth. In particular, SPIDER relies on an accurate phase calibration measurement that is normally conveniently done with the second harmonic of the two replica pulses. This measurement faces the same bandwidth limitation as second-harmonic based FROG. It therefore seems appealing to combine the advantageous phase-matching properties of third-order effects like self-diffraction with the insensitivity of SPIDER against beam smearing artifacts. Here we experimentally demonstrate a self-diffraction SPIDER apparatus and discuss necessary adaptions of the phase retrieval procedure.

© 2015 IEEE