N. Dimitrov, M. Zhekova, Y. Zhang, G. G. Paulus, and A. Dreischuh,
Among the existing techniques for measuring ultrashort pulse durations, the two classical second-order methods – interferometric and the background-free autocorrelation – are distinguished due to their simplicity and reliability. In this work we report on a technique that allows realignment-free switching between these two modes of autocorrelation. It is based on a collinearly aligned inverted-field interferometer and an optical vortex plate that is added/removed in front of the device in order to switch between both modes. Experiment and theoretical modeling confirm the effectiveness of the technique down to the 10-fs range.