The Study Of High Sensitivity Optical Nonlinear Dynamics Measurement Technology

Nonlinear optical materials have a great application prospect in all-optical switches and optical information technology. Convenient and reliable measurements are the necessary tools to research nonlinear optical materials. Many various measurement methods have been proposed. Scientists have done a lot of improvements to increase the measurement scope and sensitivity of systems.In this paper, disk Z-scan measurement technology based on the top-hat Z-scan is introduced. In this method, a combination of a circular disk and an aperture replacing the hole in the farfield of the top-hat Z scan are used, so that only high frequency signals in the outer part of pulses are selected and measured in order to improve the sensitivity of measurement systems. We applied this method in studying optical nonlinearity of an electrostatic self-assembly phthalocyanine copper thin film with minor nonlinear phase shift under the picoseconds pulses, our results show that the film has a strong refraction and the normalized transmittance has a single-peak shape.Based on the disk Z-scan measurement technology we introduced into a pump device with time delay system, and proposed a method of studying the nonlinear dynamics of materials with high sensitivity, which is called disk pump-probe technique. Pump-probe technique has two orders of magnitude advantaged over time-resolved pump probe technology with phase object of same experimental conditions in measuring the nonlinear refraction of CS2 solution. We further studied the optical nonlinearity of DMF with weak nonlinear response by applying this new measurement method.