基于二次相位超表面的大视场紧凑型全Stokes偏振测量方法

偏振是光的固有属性之一，然而传统的光强、光谱探测技术会造成电磁波的偏振信息的丢失。同时，基于偏振测量的器件及技术不仅存在视场局限的问题，而且系统复杂。基于介质型超表面设计了一种紧凑型大视场偏振探测器件，实现了对入射光的角度及偏振态的探测。该器件由2×2的二次相位超表面组成，每个超表面可实现对特定偏振的对称性变换，即将入射角旋转对称性转变为焦平面内焦点平移对称性。二次相位的对称性变换理论使得此文可以在宽角度范围内（-40°~+40°）通过测量焦点的偏移量实现对入射角的表征。在此基础上，分析了斜入射对测量Stokes参数的影响，得到矫正的Stokes公式。利用4个焦点的强度和矫正的Stokes公式可计算出入射光的Stokes参数。在视场角为0°、20°、40°时，测量的Stokes参数与理论值吻合良好。

Large field-of-view and compact full-Stokes polarimetry based on quadratic phase metasurface

Polarization is one of the inherent characteristics of light, but the polarization information of electromagnetic waves is lost by traditional intensity and spectral detection technology. At the same time, not only the devices and technologies based on polarimetry have the problem of limited field of view, but also the measuring systems are complicated. In this paper, a compact large field-of-view polarimeter was designed based on dielectric metasurface, which realized the detection of the angle and polarization state of the incident light. The device was composed of 2×2 quadratic phase metasurfaces, each of which realized the symmetry transformation for a specific polarization, that is, the rotational symmetry of the incident angle was converted into the translational symmetry of focus in the focal plane. The theory of the symmetry transformation of the quadratic phase made it possible to characterize the angle of incidence by measuring the offset of the focus over a wide angle range (?40°—+40°). On this basis, the influence of oblique incidence on the measurement of Stokes parameters was elaborated, and the modified Stokes formula was obtained. The Stokes parameters of the incident light can be calculated by utilizing the intensities of the four focal points and the modified Stokes formula. The measured Stokes parameters agree well with the theoretical values, when the field-of-view is 0°, 20°, and 40°.