Data Acquisition And Processing In Secong-Order Optical Nonlinear Coefficient Measuring Platform

Second-Order optical nonlinear coefficients are the important parameter for optical nonlinear crystals. Second-Order optical nonlinear coefficients are measured using Maker fringers, if crystals can' t achieve phase match, or some coefficients are not included in phase match. This thesis chiefly researched and realized data acquisition and data processing in the measurement of Second-Order optical nonlinear coefficient using Maker fringers.The experimental platform of Second-Order optical nonlinear coefficients measuring using Maker fringers consists of laser , rotating platform, detector, gated integrators , etc. The requisite synchronization of laser, detector, sample, and rotating platform is so rigid that manual operation can't be achieved . 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. The Maker fringers technique we used is a relative measurement, it need high repetition. 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. We studied all sorts of instruments ports, and designed specifically the software PortMaster to control data gathering. It makes data gathering automatable, and enhances the accuracy of gathering results and the efficiency of experiments greatly.The crucial question in Maker fringers experiment is how to gather the generated second-harmonic power of crystal samples in different rotating angles. 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. The whole process is controlled by computer via PortMaster. This thesis detailedly depicted the sequence control in experiment and how to improve the accuracy of experimental data, etc.Hundreds of data are collected in each experiment, and it is convenient to manage data by computer software. At present, specific software to process Maker fringers are few, and the function of them is not perfect. Such as, some are only suitable for medial and high symmetry crystals, but are not for low symmetry crystals. We specifically designed data processing software MakerDP, based on the theory formulas of Maker fringers and the features of experimental data. We can draw curves based on the input formulas. We also may input experimental data and draw experimental curves. In one chart, experimental curve and theory curve are compared. We can calculate the Second-Order optical nonlinear coefficients, after Integrating and analyzing the experimental data in MakerDP. MakerDP is suitable both for medial and high symmetry crystals and for low symmetry crystals.The instrument and software in this experimental platform accommodate changes in Maker fringers technique, and is predicted to use widely.