A Non-scanning Reflection Technique (NRT) for measurements of optical nonlinearities

Reflection Z-scan technique allows the measurements of optical nonlinearities of highly absorbing media and surface of transparent media, when transmission Z-scan can not be used. However, Reflection Z-scan needs multiple measurements under strong laser pulse excitation in the scanning process. This can induce damage in the sample in some cases. In this paper, a Non-scanning Reflection Technique (NRT) for measurement of optical nonlinearities is presented to overcome this drawback. Both the nonlinear refraction index and nonlinear absorption coefficient can be determined by measuring the reflection in combination of variable attenuator and an aperture. Based on the Fresnel theory, a theoretical analysis of Non-scanning Reflection Technique (NRT) demonstrates the feasibility of this approach is given and a general expression for the normalized reflectance is derived. In order to illustrate our analytical results, we performed a numerical simulation of the normalized reflectance. Besides, retardance and size of the induced phase plate also make contributions to the normalized reflectance. Moreover, this technique shows a higher sensitivity property compared with traditional reflection Z-scan method.