Research On Multi-parameter Full Polarization State Detection System Based On Polarization Modulation Method

The state of polarization of light refers to the mapping state of light wave vibration in a plane perpendicular to the propagation direction.Polarization detection has a wide range of applications in optical fiber communication,polarization imaging,biomedicine and other fields.Traditional polarization detectors mostly realize the detection of a single or a small number of polarization parameters of completely polarized light.With the development of polarization measurement technology,the demand for full polarization state and multi-parameter polarization detection instruments is increasing,and related independent products are still lacking in China.The research and development of such instruments is of great significance.In this paper,an optical polarization detection system for multi-parameter measurement of full polarization is studied.Based on the principle of polarized light modulation,a multi-polarization parameter measurement method that can realize fully or partially polarized light is proposed.Based on embedded and virtual instrument technology,a system prototype is developed to realize graphical real-time monitoring of polarization state.The main research contents are as follows:(1)Research on the detection method of light polarization based on polarization modulation of rotating wave plate.The polarization modulation structure is designed by using the phase delay characteristics of a quarter-wave plate and the detection characteristics of a polarizer;the polarization modulation principle and demodulation method of the structure are analyzed theoretically;a Stokes parameter solution algorithm based on complex Simpson is proposed,The feasibility of the algorithm to improve the calculation accuracy was verified by simulation;the relationship between the number of polarized light samples and the measurement error during the wave plate rotation period was discussed,and a theoretical basis was provided for system design.(2)The design of light polarization detection system based on polarization modulation of rotating wave plate.A polarization modulation mechanical structure based on a rotating wave plate and a fixed polarizer was fabricated.Based on the STM32F103 microcontroller,a polarization modulation signal conditioning and control circuit is designed.The host computer analysis software was designed using Lab VIEW,and the functions of calculation of polarization parameters,graphic display based on Poincare sphere and dynamic trajectory tracking were realized.(3)Test and analysis of polarization detection system.Set up a testing experiment platform to test the performance of the system under partially and fully polarized light input conditions.The experimental results show that the system can analyze the polarization state of the input light in the range of-50 d Bm ? + 7 d Bm;the Stokes parameter measurement error is: S1 = 1.69%,S2 = 1.71%,S3 = 1.81%;degree of polarization(DOP)error is 1.65%,degree of circular polarization(DOCP)error is1.79%,degree of linear polarization(DOLP)error is 1.54%;azimuth(?)accuracy is0.23 °;ellipticity(?)accuracy is 0.52 °;state of polarization sampling frequency F =8Hz.Through comparative testing,it reaches the test level of similar foreign products.The optical polarization detection system developed in this paper has the characteristics of portable,low cost,high accuracy,large dynamic range of input optical power,comprehensive measurement of polarization parameters,graphic display and dynamic tracking.It is suitable for field measurement,laboratory research and other applications,and promotes the development of polarization detection instruments in China.