Proceedings Article | 1 November 2021
KEYWORDS: Polarization, Error analysis, Polarizers, Photodiodes, Polarimetry, Modulation, Linear polarizers, Wave plates
Polarization is a basic and important parameter of light, and polarized light has great applications in optical communications, satellite remote sensing, optical signal processing and display, etc. High-accuracy measurement of the polarization characteristics of light is essential, and a widely-used measurement method is to obtain the full-Stokes vector with a fully-automatic polarimetry (FAP), where rotating a quarter-waveplate and using the Fourier analysis are two key points. The FAP has obvious advantages in real-time detection and high measurement accuracy, which enables polarization parameters of light, such as the degree of polarization (DoP) and the angle of polarization (AoP), to be obtained efficiently. As for FAP, systematic analyses on its measurement errors are still crucial. In this paper, we analyze the errors of FAP in terms of its three components: the quarter-waveplate, the linear polarizer and the photodiode. Firstly, the position error of the quarter-waveplate affects its fast-axis orientation, and the wavelength of light affects the retardance; secondly, the position error of the fixed polarizer disables it from the ideal vertical polarization orientation; thirdly, the intensity error of light measured by photodiode in FAP is sensitive to wavelength, and thus inevitably leads to a wavelength-dependent response. In fact, the position errors from quarter-waveplate and polarizer alter their Mueller matrices and thus finally influence the demodulation of the full-Stokes vector, while the errors from the photodiode affect the detected intensities used for Fourier analysis. In order to reduce above errors, we simulate the position errors of the quarter-waveplate and the polarizer to guide the installation of optical elements in FAP, which have great influences on demodulating the full-Stokes vector of light, we verify the feasibility of wavelength-based compensation for retardance error of quarter-waveplate, and we measure the wavelength response of the photodiode to compensate the photodiode’s error.
