Characterization of thermo-optical and third-order nonlinear optical properties by eclipse I-scan

Characterization of the nonlinear refractive index and photothermal properties are essential for the application of new photonic materials. The advantages and limitations of the commonly used techniques are related to the material analyzed and the available optical source properties. Here we propose a novel modification of the I-scan experimental setup, the intensity scan technique, adding eclipse detection. The eclipse intensity scan, EI-scan, makes this technique more sensible, providing better signal noise than the current I-scan method. Compared to standard Z-scan procedures, I-scan techniques have better performance in analyzing samples with non-parallel surfaces and samples that degrade when interacting with high-intensity pulses. From the developed analytical model, a fit expression for the EI-scan is presented. We measured thermal effects produced by high repetition pulse rates and electronic effects produced by third-order optical nonlinear interaction in I-scan techniques. In both cases, this new method demonstrated the increase in sensitivity and the gain in signal-to-noise ratio.