Graphene-based photodetectors have attracted much attention due to their unique properties, such as high-speed and wide-band detection capability. However, they suffer from very low external quantum efficiency in the infrared (IR) region and lack spectral selectivity. Here, we construct a plasmon-enhanced macro-assembled graphene nanofilm (nMAG) based dual-band infrared silicon photodetector. The Au plasmonic nanostructures improve the absorption of long-wavelength photons with energy levels below the Schottky barrier (between metal and Si) and enhance the interface transport of electrons. Combined with the strong photo-thermionic emission (PTI) effect of nMAG, the nMAG–Au–Si heterojunctions show strong dual-band detection capability with responsivities of 52.9 mA/W at 1342 nm and 10.72 mA/W at 1850 nm, outperforming IR detectors without plasmonic nanostructures by 58–4562 times. The synergy between plasmon–exciton resonance enhancement and the PTI effect opens a new avenue for invisible light detection.

中国工程物理研究院红外太赫兹自由电子激光装置是一台用于材料、光谱、生物、医学等领域前沿研究的多功能用户装置，在实验室现有的太赫兹自由电子激光装置（CTFEL）基础上，拟新增两套2×9-cell超导加速单元和两台波荡器，将电子能量提升至最大50 MeV，输出频率覆盖范围拓展至0.1~125 THz，最大宏脉冲功率大于100 W。同时，采用跑道型束线设计，拟建设一台小型能量回收型直线加速器实验研究平台。本文主要介绍了中国工程物理研究院红外太赫兹自由电子激光装置的总体设计、工作模式以及用户实验站布局。

We report the effective slowing and trapping of Cs atoms in an ultrahigh-vacuum apparatus. The heated Cs atoms in an oven are slowed using a Zeeman slower after the oven chamber and then trapped using a magneto-optical trap in a science chamber. Compared to the traditional vacuum pressure of ~10^-7 Pa determined by the vapor pressure of Cs atoms in the oven chamber, the designed cold nipple and differential pumping tube are used between the oven and the oven chamber to achieve a lower vacuum pressure of ~3.6×10^-9 Pa. This is beneficial for achieving and maintaining an ultrahigh vacuum in the science chamber. We demonstrate the performance of our apparatus through the effective slowing of Cs atoms and an optimal magneto-optical trap.

太赫兹调制器作为太赫兹技术应用的重要器件之一，在太赫兹通信、成像和传感等领域具有广泛应用前景。但是目前太赫兹调制器调制深度、工作带宽、稳定性等有待提升，这制约了太赫兹技术的进一步推广与发展。基于此，设计并制备了一种新型光控砷化镓/侧边抛磨太赫兹光纤（SPTF）调制器，将砷化镓转移到太赫兹光纤抛磨区，增强太赫兹波倏逝场与砷化镓相互作用。在外置808 nm激光器照射下实现对太赫兹波幅度调制，调制深度达到97.4%。实验结果表明，这种新型的光纤调制器具有较好的光控调制效果。同时，该器件体积小、集成度高，具有广泛应用的潜力。

随着大数据时代的到来，空间光通信已被广泛应用于各种通信系统中，但随之而来的是容量瓶颈的挑战。基于光场频率、时间、偏振、横向空间模式等维度调控的信息编解码方法在解决容量问题方面展现了优异性能，但光场的纵向维度却未被应用于信息编解码。针对此问题，本文提出了一种基于电介质超表面的光场纵向维度信息编解码新方法，基于四原子结构的几何相位和传输相位联合调控，实现了透射场自旋相关的复振幅调控。同时，利用光学冻结波原理产生了轨道角动量模式叠加态的纵向可控变化，并验证了光场模态的纵向调控能够以指数级提升信道中的模态容量。纵向维度作为一个全新的编码自由度，有望进一步提高自由空间光通信性能。

The spin Hall effect of a light beam is essentially a product of circular birefringence but is rarely demonstrated. Here, we provide a scheme for initiating off-axis circular birefringence based on the spin-dependent wave vector bifurcation of Bessel beams via a single liquid crystal Pancharatnam–Berry phase element. The tilted Bessel beam shows a detectable photonic spin Hall effect. By introducing the nonlinear propagation trajectories, the spin Hall effect is greatly enhanced. More surprisingly, the two spin states exactly propagate along the scaled trajectories, enabling flexible control of the spin separation. This phenomenon is also applicable to other Bessel-like beams with nonlinear trajectories, which have been already reported.

宫颈异常细胞特征细微难以提取、小目标容易漏检、细胞边界回归不准确导致异常细胞检测精度不高，鉴于此，本文提出了一种结合注意力的全尺度特征融合RetinaNet（AFF-RetinaNet）宫颈异常细胞检测算法。首先，采用ResNeSt-50作为特征提取网络提取宫颈异常细胞的细微特征；其次，引入平衡特征金字塔（BFP）结构，对所有特征层进行全尺度融合，增强小目标的语义信息，并利用BFP中的非局部注意力模块获取图像的全局信息，以进一步增强特征空间的语义信息；最后，采用CIoU Loss作为回归分支的损失函数，以提高对异常细胞边界回归的准确率。另外，针对实际应用场景，基于AFF-RetinaNet算法实现了全视野宫颈细胞病理学图像（WSI）推理流程，并基于该推理流程对WSI中的异常细胞进行了检测。AFF-RetinaNet在宫颈异常细胞数据集上的平均精度均值（mAP）为83.4%，其中对小目标的mAP值（mAP-s）达到了24.4%，相较于基准RetinaNet算法分别提高了3.2个百分点和10.8个百分点。基于AFF-Retina的WSI推理结果在感兴趣区域中的mAP为70.8%。实验结果表明：AFF-RetinaNet算法可以增强对小尺寸异常细胞的检测能力，有效提升宫颈异常细胞的检测精度。基于AFF-RetinaNet的宫颈WSI推理流程可辅助医生快速定位高分辨率宫颈WSI中的异常细胞，有望减轻医生的阅片负担。

We numerically demonstrate that the tight focusing of Bessel beams can generate focal fields with an ultra-long depth of focus (DOF). The ultra-long focal field can be controlled by appropriately regulating the order of the Bessel function and the polarization. An optical needle and an optical dark channel with nearly 100λ DOF are generated. The optical needle has a DOF of ∼104.9λ and a super-diffraction-limited focal spot with the size of 0.19λ2. The dark channel has a full-width at half-maximum of ∼0.346λ and a DOF of ∼103.8λ. Furthermore, the oscillating focal field with an ultra-long DOF can be also generated by merely changing the order of the input Bessel beam. Our results are expected to contribute to potential applications in optical tweezers, atom guidance and capture, and laser processing.

烧蚀效应是高超声速飞行器目标特性分析评估中的重要问题之一。基于高温反应气体动力学方程与辐射输运方程，建立了飞行器表面防热材料热化学烧蚀流场及其红外辐射特性的计算模型和方法。以钝锥体弹头外形及其表面防热材料碳-碳为对象，研究了材料烧蚀效应对再入目标流场红外辐射特性的影响，分析了再入体烧蚀流场及尾流在不同波段红外辐射的分布特征和变化规律。研究发现：典型状态计算结果与试验测量及文献预测结果一致，表明烧蚀流场及红外辐射模型和方法的可行性；材料热化学烧蚀现象对再入流场红外辐射特性产生严重影响，使3~8 μm波段尾流积分辐射强度增加一个量级以上，并随着尾流长度增加而增大；烧蚀流场红外辐射主要来自CO、NO和CO₂等化学组分，烧蚀对1~3 μm波段流场红外辐射影响相对较弱；再入速度不变情况下，烧蚀流场在3~8 μm波段红外辐射强度随再入高度降低而增强；再入高度不变情况下，烧蚀流场在同样波段红外辐射强度随着再入速度减小而减弱。

本研究利用搭建的高精度单颗粒偏振光谱表征系统，测量了六方相NaYF₄：Sm³⁺和单斜相BiPO₄：Sm³⁺单颗粒微米晶体的偏振发光特性，并结合偏振庞加莱球法和偏振拟合法对偏振发光峰进行了分析。结果表明，两种晶相中的Sm³⁺离子均发射部分偏振光，不同的是，六方相发光峰的线偏角精确沿着或垂直于结晶c轴，而单斜相发光的线偏角与结晶c轴存在非平行或正交的夹角。基于局部点群对称性和晶体宏观对称性，揭示了六方相发光峰的正交线偏角起源于光学跃迁偶极子绕结晶c轴的旋转对称分布，而单斜相中偶极子不具备旋转对称性，导致其发光峰的线偏角随机取向。该发现对于利用晶体结构获得具有理想偏振发光特性的稀土单颗粒晶体具有指导意义。