Nonlinear refraction and absorption spectra of GaP crystal measurements for all-optical switches figure-of-merit determination

Measuring the material's third-order nonlinear optical refraction (NLR) and absorption (NLA) spectra over a broad wavelength range remains challenging and time consuming. Nevertheless, it is crucial to know these spectra to establish the material's potential for photonic applications, the best spectral range for a specific application, etc. GaP is an important nonlinear material which its NLR and NLA still not fully determined over a broad wavelength range for all-optical switching (AOS) applications, for instance. Here, we have determined the figure-of-merit (FOM) spectrum of a GaP crystal (100-cut) for ultrafast AOS applications based on its nonlinear properties. Using ultrafast laser pulses from an optical parametric amplifier, we performed openaperture Z-scan measurements associate to the nonlinear ellipse rotation (NER) effect to determine simultaneously the NLR and NLA spectra. In addition, besides its wavelength dependence, we measured the FOM as a function of the crystal orientation. We observed that the crystal orientation is very critical to attains high or low FOM values.