H₂S，CH₄多组分气体浓度测量技术的研究对石油石化行业的安全生产有重要意义。基于中红外TDLAS技术， 选用中心波长为8.309 μm的量子级联激光器(Quantum Cascade Laser,QCL)为检测光源，搭建30 m长距离的遥测实验系统，使用WMS波长调制法对H₂S，CH₄气体的吸收谱线进行连续调谐与扫描，并对高频正弦载波进行了最优深化调制，实现了H₂S，CH₄多组分气体的同时测量。实验将H₂S与5%体积分数的高浓度水汽进行混合测量，分析并验证了该波段的水汽吸收难以对测量造成交叉干扰的优良特性，并利用Savitzky-Golay平滑滤波器提高了检测信号的信噪比。通过遥测实验，分析了15 m，30 m不同遥测距离对检测信号的影响，并利用增加积分时间与计算信噪比的方法，得到了128.75×10^-9 m的遥测最低限。最后，Allan方差的计算结果表明，当积分时间为183 s，142 s时，系统对H₂S，CH₄气体的最低检测下限分别为0.593×10^-9和1.160×10^-9。本文的研究结果为中红外波段H₂S，CH₄多组分气体的高灵敏度、同时测量提供了一种有效途径，为多组分气体的遥测应用提供了参考。

针对当前基于深度学习的遥感图像超分辨率重建模型部署时对硬件要求较高，本文设计了一种轻量级基于重参数化的残差特征遥感图像超分辨率重建网络。首先，采用重参数化方法设计了一种残差局部特征模块，以有效地提取图像局部特征；同时考虑到图像内部出现的相似特征，设计了一个轻量级的全局上下文模块对图像的相似特征进行关联以提升网络的特征表达能力，并通过调整该模块的通道压缩倍数来减少模型的参数量和改善模型的性能；最后，在上采样模块前使用多层特征融合模块聚合所有的深度特征，以产生更全面的特征表示。在UC Merced遥感数据集上进行测试，该算法在遥感图像3倍超分辨率下的参数量为539 K，峰值信噪比为30.01 dB，结构相似性为0.844 9，模型的推理时间为0.010 s；而HSENet算法的参数量为5 470 K，峰值信噪比为30.00 dB，结构相似性为0.842 0，模型的推理时间为0.059 s。实验结果表明，该算法相比HSENet算法，参数量更少，运行速度较快，且峰值信噪比与结构相似性也有一定的提高。在DIV2K自然图像数据集上进行测试，该算法的峰值信噪比和结构相似性相比其他算法也有一定的优势，表明该算法的泛化能力较强。

The evolution of ablative Rayleigh–Taylor instability (ARTI) induced by single-mode stationary and time-varying perturbations in heat flux is studied numerically in two dimensions. Compared with the stationary case, time-varying heat-flux perturbation mitigates ARTI growth because of the enhanced thermal smoothing induced by the wave-like traveling heat flux. A resonance is found to form when the phase velocity of the heat-flux perturbation matches the average sound speed in the ablation region. In the resonant regime, the coherent density and temperature fluctuations enhance the electron thermal conduction in the ablation region and lead to larger ablation pressure and effective acceleration, which consequently yield higher linear growth rate and saturated bubble velocity. The enhanced effective acceleration offers increased implosion velocity but can also compromise the integrity of inertial confinement fusion shells by causing faster ARTI growth.

A polarization-insensitive mode-order converting power splitter using a pixelated region is presented and investigated in this paper. As TE₀ and TM₀ modes are injected into the input port, they are converted into TE₁ and TM₁ modes, which evenly come out from the two output ports. The finite-difference time-domain method and direct-binary-search optimization algorithm are utilized to optimize structural parameters of the pixelated region to attain small insertion loss, low crosstalk, wide bandwidth, excellent power uniformity, polarization-insensitive property, and compact size. Experimental results reveal that the insertion loss, crosstalk, and power uniformity of the fabricated device at 1550 nm are 0.57, -19.67, and 0.094 dB in the case of TE polarization, while in the TM polarization, the relevant insertion loss, crosstalk, and power uniformity are 0.57, -19.40, and 0.11 dB. Within a wavelength range from 1520 to 1600 nm, for the fabricated device working at TE polarization, the insertion loss, crosstalk, and power uniformity are lower than 1.39, -17.64, and 0.14 dB. In the case of TM polarization, we achieved an insertion loss, crosstalk, and power uniformity less than 1.23, -17.62, and 0.14 dB.

We propose and experimentally realize a class of quasi-one-dimensional topological lattices whose unit cells are constructed by coupled multiple identical resonators, with uniform hopping and inversion symmetry. In the presence of coupling-path-induced effective zero hopping within the unit cells, the systems are characterized by complete multimerization with degenerate -1 energy edge states for open boundary condition. Su–Schrieffer–Heeger subspaces with fully dimerized limits corresponding to pairs of nontrivial flat bands are derived from the Hilbert spaces. In particular, topological bound states in the continuum (BICs) are inherently present in even multimer chains, manifested by embedding the topological bound states into a continuous band assured by bulk-boundary correspondence. Moreover, we experimentally demonstrate the degenerate topological edge states and topological BICs in radio-frequency circuits.

A flexible-grid 1×(2×3) mode- and wavelength-selective switch which comprises counter-tapered couplers and silicon microring resonators has been proposed, optimized, and demonstrated experimentally in this work. By carefully thermally tuning phase shifters and silicon microring resonators, mode and wavelength signals can be independently and flexibly conveyed to any one of the output ports, and different bandwidths can be generated as desired. The particle swarm optimization algorithm and finite difference time-domain method are employed to optimize structural parameters of the two-mode (de)multiplexer and crossing waveguide. The bandwidth-tunable wavelength-selective optical router composed of 12 microring resonators is studied by taking advantage of the transfer matrix method. Measurement results show that, for the fabricated module, cross talk less than -10.18dB, an extinction ratio larger than 17.41 dB, an in-band ripple lower than 0.79 dB, and a 3-dB bandwidth changing from 0.38 to 1.05 nm are obtained, as the wavelength-channel spacing is 0.40 nm. The corresponding response time is measured to be 13.64 µs.

复合折射透镜（compound refractive lens, CRL）因具有结构紧凑、焦距可调、准直方便等优点，被用作硬X射线自由电子激光（X-ray free electron laser, XFEL）装置的光束聚焦器件。面向XFEL光束高精度聚焦对高性能CRL的实际需求，从CRL的几何结构设计原理出发，分析了不同材料CRL的性能参数，证明了单晶金刚石材料是适用于XFEL光束聚焦的CRL优选材料。同时，考虑超硬金刚石材料的难加工特性以及低重频钛宝石飞秒激光不能实现大厚度材料高效加工的实际问题，探索了高重频光纤飞秒激光对大厚度单晶金刚石材料进行高效加工的可行性。研究结果表明，高重频飞秒激光精密加工技术是实现金刚石CRL制备的有效手段。