In this work, a novel one-time-programmable memory unit based on a Schottky-type p-GaN diode is proposed. During the programming process, the junction switches from a high-resistance state to a low-resistance state through Schottky junction breakdown, and the state is permanently preserved. The memory unit features a current ratio of more than 10³, a read voltage window of 6 V, a programming time of less than 10^?4 s, a stability of more than 10⁸ read cycles, and a lifetime of far more than 10 years. Besides, the fabrication of the device is fully compatible with commercial Si-based GaN process platforms, which is of great significance for the realization of low-cost read-only memory in all-GaN integration.

Dynamic infrared thermal camouflage technology has attracted extensive attention due to its ability to thermally conceal targets in various environmental backgrounds by tuning thermal emission. The use of phase change materials (PCMs) offers numerous advantages, including zero static power, rapid modulation rate, and large emissivity tuning range. However, existing PCM solutions still encounter several practical application challenges, such as temperature uniformity, amorphization achievement, and adaptability to different environments. In this paper, we present the design of an electrically controlled metal-insulator-metal thermal emitter based on a PCM metasurface, and numerically investigate its emissivity tunability, physical mechanisms, heat conduction, and thermal camouflage performance across different backgrounds. Furthermore, the influence of the quench rate on amorphization was studied to provide a guidance for evaluating and optimizing device structures. Simulation results reveal that the thermal emitter exhibits a wide spectral emissivity tuning range between 8 and 14 μm, considerable quench rates for achieving amorphization, and the ability to provide thermal camouflage across a wide background temperature range. Therefore, it is anticipated that this contribution will promote the development of PCM-based thermal emitters for practical dynamic infrared thermal camouflage technology with broad applications in both civilian and military domains.

The development of high-brightness X-ray free electron lasers (XFELs), such as hard X-ray self-seeding free electron lasers and XFEL oscillators (XFELOs), brings a severe challenge to the crystal monochromator due to a strong non-uniform thermal load. The distortion caused by spatial temperature gradients can severely affect the optical performance of crystals. Therefore, this paper presents a model to estimate the performance of non-uniform thermally distorted crystals. The model not only takes into account thermal strain, slope error and incident angle deviation, but also considers temperature-dependent factors such as the Debye–Waller factor and electric susceptibility. Our investigation indicates that the Debye–Waller factor reduces the height and bandwidth of rocking curves, and the impact of the electric susceptibility is tiny. The proposed model can describe the distortion of the reflectivity and transmissivity curves of non-uniform thermally loaded crystals and can be applied in the design of crystal monochromators, crystal splitters, crystal compressors and XFELOs.

提出基于束流相空间拍频产生锁模多色自由电子激光的方案，利用带有能量啁啾的电子束流和上海软X射线自由电子激光装置（SXFEL）上的两个调制段-色散段结构，在束流中通过拍频形成多个流强脉冲串，并在此基础上进行高次谐波辐射，产生锁模多色自由电子激光辐射脉冲。模拟结果表明，利用264 nm的种子激光，可在束流中形成18次谐波的群聚分量，并能最终产生中心波长约14.58 nm 的锁模多色FEL辐射。

Attosecond soft X-ray pulses are of great importance for the study of ultrafast electronic phenomena. In this paper, a feasible method is proposed to generate isolated fully coherent attosecond soft X-ray free electron laser via optical frequency beating. Two optical lasers with the opposite frequency chirps are used to induce a gradient frequency energy modulation, which helps to generate a gradually varied spacing electron pulse train. Subsequently, the undulator sections with electron beam delay lines are used to amplify the target ultra-short radiation. Numerical start-to-end simulations have been performed and the results demonstrate that an isolated soft X-ray pulse with the peak power of 330 GW and pulse duration of 620 as can be achieved by the proposed technique.