视频超分辨率（Video-Super Resolution，VSR）旨在将低分辨率视频帧序列重建为高分辨率视频帧序列。相较于图像超分辨率，VSR由于增加了时间维度的信息，因此通常需要依赖邻近帧高度相关信息实现当前帧的重建。如何对齐相邻帧，并获取帧间高度相关信息，是VSR任务关注的重点问题。本文将VSR任务分为去模糊、对齐、重建三个阶段。在去模糊阶段，将当前帧与相邻帧进行预对齐 ，获取与当前帧高度相关的特征信息，通过强化当前帧的细节以便实现初始阶段更多特征信息的提取。在对齐阶段，通过对输入特征进行二次对齐操作，利用相邻帧中高度相关信息进一步强化当前帧中特征信息。在重建阶段，通过聚合原始低分辨率帧以在网络末端提供更多特征信息。本文利用多层感知机（Multi-Layer Perceptron，MLP）代替传统卷积操作构造特征提取模块，同时对生成的特征信息进行二次对齐，以细化图像特征获得更优的视频帧重建效果。实验结果表明，本文提出的算法在多种公开数据集上的视频帧序列重建精度更高的同时，也取得了更少的网络参数量和更连贯的视频序列重建表现。

为了提高太赫兹超透镜成像的纵向容忍度，设计了一种纯几何相位全介质长焦深超构表面透镜器件。采用纯几何相位自旋解耦的设计方法，并结合时域有限差分（FDTD）方法，对设计的超构表面透镜进行了数值仿真。研究结果表明，所设计的太赫兹超构表面透镜具有偏振可控和长焦深的特性，在沿着传播方向上焦深达到了8 mm，而普通超构表面透镜只有4.5 mm焦深。设计并数值仿真验证了两个太赫兹长焦深聚焦复用的超构表面透镜，并使得横向复用的两个长焦深焦点具有相互正交的偏振态。相关研究有望应用于层析成像和信息加密等方面。

近年来LaNiO₃(LNO)作为铁电超晶格、超导异质结和催化剂材料引起了广泛关注。本研究采用简便、低成本的高分子辅助沉积法(Polymer Assisted Deposition, PAD), 在(001)取向的SrTiO₃(STO)单晶衬底上制备了导电性能优异的LNO外延薄膜, 并对其进行各种结构和电学表征。摇摆曲线半高宽为0.38°, 表明LNO薄膜结晶度良好。高分辨XRD的φ扫描进一步证实LNO薄膜在STO衬底上异质外延生长。原位变温XRD测试进一步表征了LNO薄膜的外延生长过程。结果表明, 聚合物分解之后金属阳离子在单晶基体上有序释放并外延结晶。XPS结果表明, 采用PAD制备的LaNiO₃薄膜不存在氧空位。薄膜表面光滑, 粗糙度为0.67 nm。在10~300 K温度区间内的变温电阻率表明LNO薄膜具有良好的导电性能。上述结果表明：PAD制备的LaNiO₃薄膜具有较好的综合性能, PAD在制备外延功能薄膜材料方面具有很大的潜力。

The investigation of converged twisted beams with a helical phase structure has a remarkable impact on both fundamental physics and practical applications. Geometric metasurfaces consisting of individually orientated metal/dielectric meta-atoms provide an ultracompact platform for generating converged vortices. However, it is still challenging to simultaneously focus left-handed and right-handed circularly polarized incident beams with pure geometric phase modulation, which hinders the independent operation on topological charges between these two helical components. Here we propose and experimentally demonstrate an approach to design terahertz geometric metasurfaces that can generate helicity-independent converged vortices with homogeneous polarization states by the superposition of two orthogonal helical vortices with identical topological charges. Furthermore, the multiplexing of polarization-rotatable multiple vortices in multiple dimensions, i.e., in both longitudinal and transverse directions, and a vortex with an extended focal depth is confirmed by embedding polarization modulation into the geometric metasurfaces. The demonstrated approach provides a new way to simultaneously manipulate orthogonal helical components and expand the design dimension, enabling new applications of geometric metasurface devices in polarization optics, twisted-beam related image and edge detection, high capacity optical communication, and quantum information processing, to name a few.

The control of spin electromagnetic (EM) waves is of great significance in optical communications. Although geometric metasurfaces have shown unprecedented capability to manipulate the wavefronts of spin EM waves, it is still challenging to independently manipulate each spin state and intensity distribution, which inevitably degrades metasurface-based devices for further applications. Here we propose and experimentally demonstrate an approach to designing spin-decoupled metalenses based on pure geometric phase, i.e., geometric metasurfaces with predesigned phase modulation possessing functionalities of both convex lenses and concave lenses. Under the illumination of left-/right-handed circularly polarized (LCP or RCP) terahertz (THz) waves, these metalenses can generate transversely/longitudinally distributed RCP/LCP multiple focal points. Since the helicity-dependent multiple focal points are locked to the polarization state of incident THz waves, the relative intensity between two orthogonal components can be controlled with different weights of LCP and RCP THz waves, leading to the intensity-tunable functionality. This robust approach for simultaneously manipulating orthogonal spin states and energy distributions of spin EM waves will open a new avenue for designing multifunctional devices and integrated communication systems.