Free space variable optical attenuator using frustrated total internal reflection with 70 dB dynamic range.

With the advance of high power laser systems, there is an increasing need to dim the corresponding light field power over larger dynamic ranges. The usual means to control the attenuation of directed light use optical filters or coatings with tailored reflectance and transmittance properties. They do not provide the variability that is often required in experiments. A system is reported here that demonstrated continuous variation of the transmittance over 70 dB, using frustrated total internal reflection.

Single shot interferometric method for measuring the nonlinear refractive index.

In this paper we are introducing a new single shot method for measuring the nonlinear refractive index of materials in a simple interferometric pump-probe configuration. The theoretical model proposed for extracting the nonlinear refractive index from the experimental fringe pattern and the experimental configuration are presented and discussed. The results obtained by this method are in good agreement with that obtained on the same sample using the conventional Z-scan method.