Frequency-resolved microscopic second-order hyperpolarizability of azochromophores: a study on nonlinear all-optical switching applications.

Azochromophores present interesting optical properties for application in all-optical switches (AOSs), such as ultrafast photoisomerization and considerable nonlinear optical response. However, determining the frequency-resolved microscopic second-order hyperpolarizability (real and imaginary parts) related to the pure electronic effects of molecules in solution is a challenging task. In this context, we have used femtosecond-laser induced nonlinear ellipse rotation (NER) measurements to obtain the electronic nonlinear refraction (()) and two-photon absorption spectra (()) of four azochromophores dissolved in methanol and acetone.

Approach to patients with COVID-19 disease: the procedure in Udine.

Coronavirus disease 2019 poses a serious threat to public health. The protocol developed at the Azienda Sanitaria Universitaria Friuli Centrale (Italy) is based on clinical data, laboratory tests, chest echography and HRCT. Several therapeutic options are considered, since patients vary in disease severity, evolution and co-morbidities and because so far there are no clear indications about therapeutic strategy based on randomized clinical trial.

Discrimination between two distinct nonlinear effects by polarization-resolved Z-scan measurements.

We investigated how the Z-scan technique can be explored to distinguish two types of nonlinear refractive effects by employing two distinct laser polarizations. It is possible that pure electronic, molecular orientation and thermal nonlinear effects may occur simultaneously during light-matter interaction. We found a way to discriminate and quantify two distinct nonlinear processes from Z-scan signals measured with linear and circular polarizations.

Cross-section profile of the nonlinear refractive index of Gorilla Glass obtained by nonlinear ellipse rotation measurements.

In this work we determined the influence of potassium-to-sodium ion exchange in the nonlinear refractive value (n) of Corning's Gorilla Glass (GG). Due to the production process, GG has a rich potassium surface in comparison to the original sodium matrix glass. In order to determine the nonlinear cross-section profile, we have used a highly sensitive nonlinear elliptical rotation spatial measurement.