Nonlinear refractive index measurement by SPM-induced phase regression

Herewith, we describe how intensity and phase of the ultrashort pulse retrieved with second-harmonic frequency-resolved optical gating (SHG FROG) can be utilized for measurement of the nonlinear refractive index (n(2)). Through comparison with available literature, we show that our method surpasses Z-scan in terms of precision by a factor of two and thus constitutes an interesting alternative. We present results for various materials: fused silica, calcite, YVO4, BiBO, CaF2, and YAG at 1030 nm. Unlike the Z-scan, the use of this method is not restricted to free-space geometry, but due to its characteristics, it can be used in integrated waveguides or photonic crystal fibers as well. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement