Dielectric super-absorbing ( > 50 % ) metasurfaces, born of necessity to break the 50% absorption limit of an ultrathin film, offer an efficient way to manipulate light. However, in previous works, super absorption in dielectric systems was predominately realized via making two modes reach the degenerate critical coupling condition, which restricted the two modes to be orthogonal. Here, we demonstrate that in nonorthogonal-mode systems, which represent a broader range of metasurfaces, super absorption can be achieved by breaking parity-time (PT) symmetry. As a proof of concept, super absorption (100% in simulation and 71% in experiment) at near-infrared frequencies is achieved in a Si-Ge-Si metasurface with two nonorthogonal modes. Engineering PT symmetry enriches the field of non-Hermitian flat photonics, opening-up new possibilities in optical sensing, thermal emission, photovoltaic, and photodetecting devices.

Three-dimensional (3D) nanofabrication techniques are of paramount importance in nanoscience and nanotechnology because they are prerequisites to realizing complex, compact, and functional 3D nanodevices. Although several 3D nanofabrication methods have been proposed and developed in recent years, it is still a formidable challenge to achieve a balance among resolution, accuracy, simplicity, and adaptability. Here, we propose a 3D nanofabrication method based on electron-beam lithography using ice resists (iEBL) and fabricate 3D nanostructures by stacking layered structures and those with dose-modulated exposure, respectively. The entire process of 3D nanofabrication is realized in one vacuum system by skipping the spin-coating and developing steps required for commonly used resists. This needs far fewer processing steps and is contamination-free compared with conventional methods. With in situ alignment and correction in the iEBL process, a pattern resolution of 20 nm and an alignment error below 100 nm can be steadily achieved. This 3D nanofabrication technique using ice thus shows great potential in the fabrication of complicated 3D nanodevices.

Intense particle beams generated from the interaction of ultrahigh intensity lasers with sample foils provide options in radiography, high-yield neutron sources, high-energy-density-matter generation, and ion fast ignition. An accurate understanding of beam transportation behavior in dense matter is crucial for all these applications. Here we report the experimental evidence on one order of magnitude enhancement of intense laser-accelerated proton beam stopping in dense ionized matter, in comparison with the current-widely used models describing individual ion stopping in matter. Supported by particle-in-cell (PIC) simulations, we attribute the enhancement to the strong decelerating electric field approaching 1 GV/m that can be created by the beam-driven return current. This collective effect plays the dominant role in the stopping of laser-accelerated intense proton beams in dense ionized matter. This finding is essential for the optimum design of ion driven fast ignition and inertial confinement fusion.

Switchable thermal emission in the long-wave infrared (LWIR, 8−14 μm) range is of great significance in applications like thermal detection, radiative cooling, and infrared camouflage. Existing methods for switchable LWIR emission apply photonic structures incorporating smart materials, which either require a continuous input power or produce limited emissivity contrasts. In this study, two nonvolatile high-contrast switchable emitters over the whole LWIR range have been proposed utilizing the drastic permittivity change of In 3 SbTe 2 (IST) upon crystallization. One switchable emitter exhibits negative differential emissivity (Δε N,8−14 μm ≈ −0.75, emissivity decreases with temperature) and is experimentally applied to infrared camouflage; the other shows positive differential emissivity (Δε P,8−14 μm ≈ 0.83, emissivity increases with temperature) and demonstrates its capability in thermal management. The demonstrated characteristics of IST provide a new route for realizing differential emissivity and make the IST-based emitters highly promising for applications such as infrared camouflage and thermal management.

The development of ultrathin, flexible, large-scale, high-temperature-tolerant infrared camouflage devices, which are immune to the external environment, has emerged as an important unsolved challenge. This paper proposes an infrared camouflage device based on the Lambertian surface. The proposed device simultaneously exhibits low emissivity (≈0.1), low specular reflectance (≈0.05), and high temperature (290°C) tolerance over a broad infrared range (0.75-25 μm). Furthermore, the proposed device is ultrathin (≈50 μm), highly flexible, scalable, and can be fabricated at a low cost. The experimental results show that while camouflaging a target (at 65°C), the proposed Lambertian surface can reduce the peak value of the target-background contrast by 68.4% (indoor case) and 76.0% (outdoor case) compared to the conventional low-e (low-emissivity) smooth surface. The calculated detection range of the proposed low-e Lambertian surface is 60% less than that of both the low-e smooth surface and the blackbody. This work proposes a novel method to simultaneously control the radiation and the reflection, thereby introducing a new design paradigm for modern camouflage technology and energy harvesting applications.