Optical metasurfaces, which consist of subwavelength scale meta-atoms, represent a novel platform to manipulate the polarization and phase of light. The optical performance of metasurfaces heavily relies on the quality of nanofabrication. Retrieving the Jones matrix of an imperfect metasurface optical element is highly desirable. We show that this can be realized by decomposing the generalized Jones matrix of a meta-atom into two parallel ones, which correspond to the ideal matrix and a phase retardation. To experimentally verify this concept, we designed and fabricated metasurface polarizers, which consist of geometric phase-controlled dielectric meta-atoms. By scanning the polarization states of the incident and transmitted light, we are able to extract the coefficients of the two parallel matrices of a metasurface polarizer. Based on the results of the Jones matrix decomposition, we also demonstrated polarization image encryption and spin-selective optical holography. The proposed Jones matrix retrieval protocol may have important applications in computational imaging, optical computing, optical communications, and so on.

Polarimetry is a highly sensitive method to quantify changes of the polarization state of light when passing through matter and is therefore widely applied in material science. The progress of synchrotron and X-ray free electron laser (XFEL) sources has led to significant developments of X-ray polarizers, opening perspectives for new applications of polarimetry to study source and beamline parameters as well as sample characteristics. X-ray polarimetry has shown to date a polarization purity of less than $1.4\times {10}^{-11}$ , enabling the detection of very small signals from ultrafast phenomena. A prominent application is the detection of vacuum birefringence. Vacuum birefringence is predicted in quantum electrodynamics and is expected to be probed by combining an XFEL with a petawatt-class optical laser. We review how source and optical elements affect X-ray polarimeters in general and which qualities are required for the detection of vacuum birefringence.

报道了一种808 nm激光二极管端面泵浦Nd：YAG激光晶体/腔内倍频的波长可调、低噪声全固态黄绿激光器。基于L型折叠谐振腔结构的优化设计，不但使谐振腔对热焦距具有动态热不灵敏性，而且补偿了折叠型结构和凹面反射镜引起的光束像散。基于布儒斯特片的布儒斯特角调节，实现对Nd：YAG晶体受激辐射产生的1 112.62 nm、1 116.70 nm和1 123.24 nm三条谱线的选频和单一波长基频光腔内振荡；调节单一波长基频光的p偏振方向与双折射单晶玻璃光轴之间的夹角，通过压缩纵模个数，实现对该波长基频光的滤波。在此基础上，通过Ⅰ类角度相位匹配LBO晶体腔内倍频，分别获得了556.31 nm、558.35 nm和561.62 nm三个波长可调、高稳定性、低噪声的黄绿激光输出，对应最大连续输出功率分别达到了678 mW、653 mW和606 mW，光光转换效率分别为8.47%、8.16%和7.58%。在输出功率均为500 mW时，功率不稳定度分别为±0.42%、±0.38%和±0.49%，对应激光噪声分别为0.69%、0.51%和0.96%。