Stereoscopic imaging reveals the 3D morphology of objects by collecting dense optical data from multiple views. However, traditional active methods rely on structured light illumination, while passive methods require substantial bulky optical components, hindering the development of portable, real-time stereoimaging systems. Here, we demonstrate miniaturized passive snapshot polarimetric stereoscopic imaging (SPSIM) using a polarimetric metalens. This protocol outperforms commercial polarimetric cameras in efficiency and enables the separation of circular polarization (CP) components for full Stokes parameter acquisition. By incorporating polarimetric physical priors into the neural network, we significantly enhance the accuracy of the 3D reconstruction process, enabling instant stereoimaging from a single shot with low mean absolute error. The inclusion of CP information improves 3D surface detail reconstruction, achieving depth precision within 0.15 mm. Our SPSIM system is well suited for integration into miniaturized devices for use in extreme environments, while advancing next-generation high-resolution 3D imaging systems.

With the exponential growth in information transmission and the escalating demand for multi-band joint detection, high-speed ultra-broadband detectors play a crucial role in aerospace technology, national security, etc. The interfacial work function internal photoemission (IWIP) detector employs the multiple absorption mechanism comprehensively across different wavelength bands to achieve complete photon-type detection, which makes it possible to realize high-speed and ultra-broadband simultaneously. We propose a ratchet heterojunction IWIP (HEIWIP) detector, which shows 3–165 THz ultra-broadband coverage. The high-speed response is investigated in detail by both microwave rectification technology and high-speed modulated terahertz light. Up to 5.1 GHz, a 3 dB bandwidth is acquired in terms of microwave rectification measurements, and a 4.255 GHz inter-mode optical beat note signal was successfully detected. The ratchet HEIWIP detector not only fulfills the demands for ultra-broadband detection but also facilitates high-speed detection, thereby significantly broadening the scope of applications for ultra-broadband detectors.

Free-electron laser (FEL) is a powerful tool that provides high-brightness radiation across a wide range of frequencies up to the x-ray spectrum. However, the large size and high cost of FEL facilities have limited their accessibility and widespread adoption. To address this challenge, researchers have explored the possibility of replicating FEL physics using lasers instead of magnetic undulators, but practical implementation has remained unattainable. This study proposes a laser-driven approach for generating high-brightness x-ray radiation. Similar to FELs, the method relies on collective coherent emission, where electrons are bunched through highly nonlinear interactions with the laser and their own radiation. This process enables high-gain undulation, a phenomenon previously exclusive to FEL facilities. We establish the fundamental scaling laws of high-gain laser undulation, identifying the upper limits of radiation peak power and brightness determined by Coulomb repulsion and quantum recoil. Promising operational regimes are highlighted, including extreme ultraviolet and soft x rays (water window) using advanced electron and laser sources, with potential extension to hard x rays through low-gain laser undulation in an oscillator configuration. These findings contribute to the ongoing pursuit of compact sources of high-brightness radiation, paving the way for more accessible and versatile x-ray sources. On the fundamental side, they open previously inaccessible regimes of strong-field electrodynamics, offering new opportunities to explore quantum phenomena in extreme conditions.