We demonstrate a high-Q perfect light absorber based on all-dielectric doubly-resonant metasurface. Leveraging bound states in the continuum (BICs) protected by different symmetries, we manage to independently manipulate the Q factors of the two degenerate quasi-BICs through dual-symmetry perturbations, achieving precise matching of the radiative and nonradiative Q factors for degenerate critical coupling. We achieve a narrowband light absorption with a >600 Q factor and a > 99% absorptance at λ₀ = 1550 nm on an asymmetric germanium metasurface with a 0.2λ₀ thickness. Our work provides a new strategy for engineering multiresonant metasurfaces for narrowband light absorption and nonlinear applications.

相位是描述光波状态的重要参数，但却无法直接观察。本文基于哈特曼探测器的波前快速探测功能，研究了光波相位三维显示的方法，并研制出相位三维显示系统。首先，利用Zemax软件对系统的光源、准直透镜等光学参数进行优化设计；然后，基于模式法波前重构理论，根据探测的Zernike多项式离焦量和像散项系数，实现了对3个不同类型镜片的相位三维显示，并给出相应屈光度的测量方法；最后，实验验证了光波相位的三维显示和屈光度测量的有效性，-2.00 D的近视镜测量值为-2.07 D，1.00 D的远视镜测量值为0.91 D，0.50 D的散光镜测量值为0.56 D。实验结果表明，此系统能够较准确地测量屈光矫正镜的屈光度，并实现相位的三维显示。本文设计的基于哈特曼探测器的相位三维显示方法具有更好的环境适应能力，便于研究者直观观测光的相位分布。

Dielectric metasurfaces play an increasingly important role in enhancing optical nonlinear generations owing to their ability to support strong light-matter interactions based on Mie-type multipolar resonances. Compared to metasurfaces composed of the periodic arrangement of nanoparticles, inverse, so-called, membrane metasurfaces offer unique possibilities for supporting multipolar resonances, while maintaining small unit cell size, large mode volume and high field enhancement for enhancing nonlinear frequency conversion. Here, we theoretically and experimentally investigate the formation of bound states in the continuum (BICs) from silicon dimer-hole membrane metasurfaces. We demonstrate that our BIC-formed resonance features a strong and tailorable electric near-field confinement inside the silicon membrane films. Furthermore, we show that by tuning the gap between the holes, one can open a leaky channel to transform these regular BICs into quasi-BICs, which can be excited directly under normal plane wave incidence. To prove the capabilities of such metasurfaces, we demonstrate the conversion of an infrared image to the visible range, based on the Third-harmonic generation (THG) process with the resonant membrane metasurfaces. Our results suggest a new paradigm for realising efficient nonlinear photonics metadevices and hold promise for extending the applications of nonlinear structuring surfaces to new types of all-optical near-infrared imaging technologies.

蓝光OLED材料是电致发光领域的关键和难点。基于高能激发态转换的“热激子”材料表现出优异蓝光材料的潜能。本文通过调节给受体的推拉电子能力，以蒽为核心构筑单元、三苯基苯为弱给体、苯氰基为受体，设计合成了一种新型D?π?A结构分子TACN。扭曲的三苯基苯提供了高度扭曲的分子构象，有效减弱了聚集态下的猝灭效应，因此TACN表现出高的荧光量子产率（聚集态下47%）。实验结果和理论分析表明，TACN具备“热激子”特征，其大的T₂?T₁能隙（1.45 eV）有效阻碍了从T₂到T₁的内转换（IC）过程，而小的T₂?S₁能差（0.18 eV，T₂> S₁）有利于促进反向系间窜越（RISC）过程。基于TACN的非掺杂器件表现出深蓝色发射（λ_max= 444 nm），半峰宽（FWHM）为59 nm，色坐标为（0.17，0.13）。其最大外量子效率（EQE_max）为8.3%，相应的激子利用率（EUE）最高为88.7%。

纳米位移测量技术是实现高精度纳米制造的基础。激光自混合干涉为精密纳米位移测量提供了一种结构简便、成本低廉，同时测量精度可达纳米量级的精密位移测量方法。区别于传统基于反射镜或散射面为反馈元件的激光自混合干涉测量方案，研究了一种基于平面反射式全息光栅的激光自混合纳米位移测量方法，该方法的位移测量结果以光栅的周期为基准。实验测得了在弱反馈强度条件下的光栅自混合干涉信号，通过阈值设定的方法确定位移方向的反转点，结合反余弦的相位解包裹算法处理光栅自混合信号，获得了对应的位移测量值。最终采用商用激光干涉仪与自组装的光栅自混合干涉仪进行位移测量数据的比对测量，实验结果表明，经过线性修正后，其位移误差不超过0.241%。

Due to the complicated film formation kinetics, morphology control remains a major challenge for the development of efficient and stable all-polymer solar cells (all-PSCs). To overcome this obstacle, the sequential deposition method is used to fabricate the photoactive layers of all-PSCs comprising a polymer donor PTzBI-oF and a polymer acceptor PS1. The film morphology can be manipulated by incorporating amounts of a dibenzyl ether additive into the PS1 layer. Detailed morphology investigations by grazing incidence wide-angle X-ray scattering and a transmission electron microscope reveal that the combination merits of sequential deposition and DBE additive can render favorable crystalline properties as well as phase separation for PTzBI-oF:PS1 blends. Consequently, the optimized all-PSCs delivered an enhanced power conversion efficiency (PCE) of 15.21% along with improved carrier extraction and suppressed charge recombination. More importantly, the optimized all-PSCs remain over 90% of their initial PCEs under continuous thermal stress at 65 °C for over 500 h. This work validates that control over microstructure morphology via a sequential deposition process is a promising strategy for fabricating highly efficient and stable all-PSCs.