THG-based third order autocorrelation for direct optical pulse-shape measurement on mode-locked Ti:sapphire lasers

Summary form only given. Direct third-harmonic-generation (THG) implementation was first realized on a modelocked Cr:forsterite laser with the method of Third Order Autocorrelation for Direct optical pulse-shape measurement (TOAD). In this report, we demonstrate this technique on the commonly used Ti:sapphire modelocked laser for the first time. By using THG process in a single GaN thin film or a thin BBO crystal, the intensity profile of the optical pulses was directly obtained with the background free third-order autocorrelation trace. In addition, we employed the Gerchberg-Saxton algorithm to retrieve the corresponding phase by the obtained intensity and an additional spectral measurement.