Metalenses have gained significant attention and have been widely utilized in optical systems for focusing and imaging, owing to their lightweight, high-integration, and exceptional-flexibility capabilities. Traditional design methods neglect the coupling effect between adjacent meta-atoms, thus harming the practical performance of meta-devices. The existing physical/data-driven optimization algorithms can solve the above problems, but bring significant time costs or require a large number of data-sets. Here, we propose a physics-data-driven method employing an “intelligent optimizer” that enables us to adaptively modify the sizes of the meta-atom according to the sizes of its surrounding ones. The implementation of such a scheme effectively mitigates the undesired impact of local lattice coupling, and the proposed network model works well on thousands of data-sets with a validation loss of 3×10^?3. Based on the “intelligent optimizer”, a 1-cm-diameter metalens is designed within 3 hours, and the experimental results show that the 1-mm-diameter metalens has a relative focusing efficiency of 93.4% (compared to the ideal focusing efficiency) and a Strehl ratio of 0.94. Compared to previous inverse design method, our method significantly boosts designing efficiency with five orders of magnitude reduction in time. More generally, it may set a new paradigm for devising large-aperture meta-devices.

Photoelectric logic gates (PELGs) are the key component in integrated electronics due to their abilities of signal conversion and logic operations. However, traditional PELGs with fixed architectures can realize only very limited logic functions with relatively low on–off ratios. We present a self-driving polarized photodetector driven by the Dember effect, which yields ambipolar photocurrents through photonic modulation by a nested grating. The ambipolar response is realized by exciting the whispering-gallery mode and localized surface plasmon resonances, which leads to reverse spatial carrier generation and therefore the contrary photocurrent assisted by the Dember effect. We further design a full-functional PELG, which enables all five basic logic functions (“AND”, “OR”, “NOT”, “NAND”, and “NOR”) simultaneously in a single device by using one source and one photodetector only. Such an all-in-one PELG exhibits a strong robustness against structure size, incident wavelength, light power, and half-wave plate modulation, paving a way to the realization of ultracompact high-performance PELGs.

Active devices have drawn considerable attention owing to their powerful capabilities to manipulate electromagnetic waves. Fast and periodic modulation of material properties is one of the key obstacles to the practical implementation of active metamaterials and metasurfaces. In this study, to circumvent this limitation, we employ a cascaded phase-matching mechanism to amplify signals through spatiotemporal modulation of permittivity. Our results show that the energy of the amplified fundamental mode can be efficiently transferred to that of the high harmonic components if the spatiotemporal modulation travels at the same speed as the signals. This outstanding benefit enables a low-frequency pump to excite parametric amplification. The realization of cascaded parametric amplification is demonstrated by finite-difference time-domain (FDTD) simulations and analytical calculations based on the Bloch–Floquet theory. We find that the same lasing state can always be excited by an incidence at different harmonic frequencies. The spectral and temporal responses of the space-time modulated slab strongly depend on the modulation length, modulation strength, and modulation velocity. Furthermore, the cascaded parametric oscillators composed of a cavity formed by photonic crystals are presented. The lasing threshold is significantly reduced by the cavity resonance. Finally, the excitation of cascaded parametric amplification relying on the Si-waveguide platform is demonstrated. We believed that the proposed mechanism provides a promising opportunity for the practical implementation of intense amplification and coherent radiation based on active metamaterials.

边界杂质注入是未来聚变装置ITER用于增强边界辐射, 减少第一壁热负荷的一种重要方法。 但部分注入的杂质会被输运到芯部, 造成主等离子体辐射损失以及约束下降。 光谱观测可以获取杂质种类、 含量和分布等信息, 在理解等离子体中杂质输运方面起着重要作用。 在EAST(experimental advanced superconducting tokamak)偏滤器氩气(Ar)注入实验中, 利用偏滤器可见光谱和芯部极紫外光谱监测边界的Ar¹⁺离子谱线Ar Ⅱ(401.36 nm)和芯部的Ar¹⁵⁺离子谱线Ar ⅩⅥ(35.39 nm), 并获得两者强度随时间的变化。 其中, Ar Ⅱ和Ar ⅩⅥ的电离能分别为27和918 eV, 因此, Ar Ⅱ和Ar ⅩⅥ分别对应分布于等离子体边界和芯部Ar离子。 为了分析二者谱线强度随时间变化的特征, 发展了一种基于正则Pearson积矩相关系数的相关分析方法, 计算得到两者谱线强度变化的相对延迟时间, 以此表征杂质从边界向芯部输运的时间。 结果显示, 偏滤器注入Ar杂质后, 芯部Ar ⅩⅥ辐射增长滞后于边界Ar Ⅱ辐射的增长, 并且在具有较高的低杂波加热功率的放电中, 两者的延迟时间较长, 表明较高的低杂波加热功率可以延长杂质从边界向芯部输运的时间。

共掺Rb⁺、Zn²⁺得到了（Cs_0.8Rb_0.2）（Pb_0.93Zn_0.07）（Br_1.8Cl_1.2）蓝光钙钛矿量子点。相比未掺杂的CsPb（Br_1.8Cl_1.2）量子点，Rb⁺、Zn²⁺与卤素离子（Br^-、Cl^-）形成更加稳定的钙钛矿八面体晶型，抑制了Cl^-空位缺陷的形成，提高了量子点的稳定性。掺杂后的量子点溶液光致发光效率从未掺杂的5%显著提高到52%，同时辐射复合也得到了显著增强。Rb⁺、Zn²⁺共掺使量子点的HOMO能级上移0.31 eV，降低了从空穴传输层（HTL）到发光层（EML）的注入势垒，有利于空穴注入。基于Rb⁺、Zn²⁺共掺的蓝光钙钛矿量子点，设计了结构为ITO/PEDOT∶PSS/TFB/Pe-QDs/TPBi/LiF/Al的发光二极管器件，得到发光峰位于470 nm、半峰宽为19 nm的蓝光发射，最大外量子效率（EQE_max）达到3.55%。

设计了空穴传输材料聚乙烯基咔唑（PVK）与绿光无镉磷化铟（InP）量子点共混体系，改善了量子点团聚效应，减少了量子点之间相互作用产生的非辐射Förster能量转移（FRET），提高了共混无镉量子点薄膜的光致发光效率（PLQY），从24.2%提升至30.1%。同时，PVK的掺入提高了共混发光薄膜的空穴传输性能，改善了量子点电致发光器件的载流子平衡，使器件的最大外量子效率（EQE）达到5.94%，较未掺杂器件提高了32%。该聚合物掺杂方法可为研制高性能绿光InP量子点发光二极管提供参考。