Method for measuring nonlinearity of material based on monopulse

Abstract

The invention discloses a method for measuring the nonlinearity of a material based on monopulse, which is characterized in that after passing through a phase object, a laser pulse with an approximate tophat profile is divided by a beam splitter into two beams, namely, a beam of monitoring light and a beam of detecting light. The measurement steps include: (1) placing a sample at a position far from a focal plane of a focusing lens for recording the energy of the monitoring light and the energy of pulsed light respectively and calculating a ratio; (2) moving the sample to the position of the focal plane of the focusing lens for recording the energy the monitoring light and the energy of the pulsed light respectively and calculating a ratio; and (3) dividing the ratio obtained in the step (2) by the ratio obtained in the step (1) to obtain a normalized nonlinear penetration rate and obtaining the nonlinear refraction coefficient of the material through processing. The method of the invention has the advantages of simple implementation, no need of movement, simple experimental data and the like; and the pulsed light with a tophat profile, adopted as the detecting light, can improve the detection precision by 4 times compared with Gaussian pulsed light.

Description

technical field [0001] The invention relates to a method for testing or analyzing materials by using optical means, in particular to a method for studying nonlinear optical physical parameters of materials, and belongs to the fields of nonlinear photonic materials and nonlinear optical information processing. Background technique [0002] The study of nonlinear optical materials has become a research hotspot in nonlinear optics today, and nonlinear optical measurement technology is one of the key technologies for studying nonlinear optical materials. The commonly used measurement methods are Z-scan (Mansoor Sheik-Bahae, Ali A. Said, Tai-Hui Wei, David J. Hagan, E.W. Van Stryland. "Sensitive measurement of optical nonlinearities using a single beam", IEEE J. Quantum Elect, 26 , 760-769(1990)), 4f system coherent imaging technology (G.Boudebs and S.Cherukul appurath, "Nonlinear optical measurements using a 4f coherent imaging system with phase object", Phys.Rev.A, 69, 053813(2...

AI Technical Summary

Problems solved by technology

However, this method requires complex processing of the collected images, and has relatively high requirements for the CCD, and the measurement cost is relatively high

The phase object Z-scan is the same as the traditional Z-scan. This measurement method also requires the movement of the sample in the direction of laser propagation and multiple excitations of the sample by the laser, which is easy to cause damage to the sample.

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