The Construction Of Second Order Nonlinear Coefficient Measuring System Based On LabVIEW

With the discovery and application of laser, the nonlinear optical phenomenon which was induced by irradiation of lasers in the materials, such as second-harmonic generation and optical parametric oscillator so on, has been applied widely especially in photonic devices. These developments of applications make the nonlinear optics become the focus of investigation of researchers. Nonlinear optical(NLO) materials are widely used in optical devices such as frequency conversion, optical parametric oscillation, optical telecommunications and modulation. A lot of researches have been done since the first observation of second-harmonic generation(SHG) in 1961.This thesis summarizes the origin and the development process of the nonlinear optics. Second-Order optical nonlinear coefficients are the important parameter for optical nonlinear crystals. Several methods to test the second-order nonlinear optical coefficients are summed up. The Maker fringe technique can be used to measure almost all of the nonlinear coefficients, and is currently the most commonly used method.So an experimental platform for Maker fringe to measure the Second-Order optical nonlinear coefficients was constructed. Firstly,We analyze the experimental principle, which we built the optical system based on. The crucial question in this experiment is how to gather the generated second-harmonic power of crystal samples in different rotating angles. The experimental platform of second-order optical nonlinear coefficients measuring using Maker fringers consists of laser,rotating platform, detector, gated integrators,etc. The angles are controlled by rotating platform accurately. The second-harmonic power is detected by detectors and integrated by Gated Integrators, then is averaged and exported. Photoelectric signals that are acquired by Maker fringers are weak ones, they are susceptible of disturbances. The more data we gather, the exacter results we’ll get. So we need to gather as many as data. Based on the features of our data gathering, we must combine the automated instruments and computer technology to accomplish our tasks of data gathering well. LabVIEW is a graphical programming language, we studied all sorts of instruments ports, and designed specifically the software based on LabVIEW, in order to realize the automation of data collection and improve accuracy to improve the experimental efficiency.