Metasurfaces, artificial two-dimensional layered materials with a sub-wavelength thickness, have gained significant interest due to their unparalleled abil

Metasurfaces, artificial two-dimensional layered materials with a sub-wavelength thickness, have gained significant interest due to their unparalleled ability to precisely manipulate the amplitude, polarization, phase, and other intrinsic properties of electromagnetic waves. In addition, the development of metasurfaces provides a new idea of “structure instead of material,” through the local enhancement of the optical field and resonance modulation, which can break through the limitations of the material’s intrinsic nonlinear effects, to realize the significant improvement of performance parameters in the sub-ps time domain. This review discusses the design principles, fabrication, and numerical simulation methods of metasurfaces, as well as their modulation characteristics of light in space and time domains. In the applications, the contribution of metasurfaces to optical modulation and imaging in the space domain is summarized, with a focus on their phase and polarization manipulation capabilities. Particularly, we are attentive to the application of metasurfaces in the time domain, probing into the relationship between metasurface structure and nonlinear optical properties, as well as the generation of pulsed lasers via mode-locked and Q-switched techniques. Finally, the developments and challenges of metasurfaces are summarized with an outlook provided to give a comprehensive understanding of metasurfaces and to facilitate their practical applications.show less

Label-free 3D tomography has attracted growing attention in biological imaging due to its inherent resistance to phototoxicity and concise system configura

Label-free 3D tomography has attracted growing attention in biological imaging due to its inherent resistance to phototoxicity and concise system configuration. Among existing techniques, Fourier ptychographic tomography (FPT) stands out for high-resolution refractive index (RI) reconstruction from noninterferometric measurements, avoiding coherent noise and phase instability—key limitations of optical diffraction tomography. However, conventional FPT suffers from significant artifacts and high computational demands, especially for multiscattering samples and long-term observation. Here, we introduce physics-informed aberration-corrected meta neural representation (PAMR), an advanced self-supervised framework that integrates neural representation with physics prior, meta-learning optimization, and adaptive aberration correction. Simulations and experiments show that PAMR produces high-fidelity 3D reconstructions with reduced artifacts and strong optical section ability, achieving 137 and 550 nm resolution for lateral and axial, respectively. Moreover, PAMR exhibits superior sparse-view robustness, sustaining high-quality with 75% view reduction. Through the meta-learning strategy, the reconstruction speed of dynamic volumes could be increased by 10 times. Applications include 3D RI imaging of multiscattering C. elegans and long-term 3D observation of HeLa cells, showing detailed organelle structures and interactions. As a generalizable approach combining computational efficiency with physical accuracy, PAMR provides an advanced algorithm for label-free 3D microscopy, with broad applicability across biomedical research.show less

Accelerator-driven systems (ADSs) may offer a promising technology for energy production and transmutation of nuclear waste. Here we introduce the concept

Accelerator-driven systems (ADSs) may offer a promising technology for energy production and transmutation of nuclear waste. Here we introduce the concept of utilizing high-intensity laser acceleration technology in realizing an ADS, with a focus on the use of thorium fuel in subcritical systems. We explore state-of-the-art laser-driven particle sources for neutron generation by nuclear fusion, spallation or photonuclear reactions and the prospect of reaching the flux of ${10}^{15}$ n/s required to drive a subcritical reactor. We review recent advances in high-power laser amplification and assess their technological readiness in view of integration in an ADS. Finally, we present a risk analysis of a laser-driven ADS in terms of laser and target development, radiation safety and operational stability. Our conclusion highlights the potential of laser-driven ADSs as a transformative approach to nuclear fission energy. With continued research and development, technological hurdles can be overcome to fully realize sustainable, green energy production that can meet global energy demands while addressing safety and environmental concerns.show less

Chip-scale laser sources capable of delivering high power and energy in the eye-safe 2 μm spectral range are essential for applications in medicine and env

Chip-scale laser sources capable of delivering high power and energy in the eye-safe 2 μm spectral range are essential for applications in medicine and environmental sensing. We report a remarkable advancement in pulsed 2 μm waveguide laser technology through the integration of high-quality large-mode-area Tm3+-doped fluoride channel waveguides with low-loss, directly deposited single-walled carbon nanotubes on cavity mirrors, serving as efficient saturable absorbers. Comprehensive characterization of these nonlinear mirrors revealed optimized chirality distribution of carbon nanotubes and favorable nonlinear absorption dynamics, enabling efficient passive Q-switching. The proposed configuration achieved a record output power exceeding 1 W and an optical efficiency over 60%—the highest reported for any pulsed, integrated 2 μm coherent light source to date, significantly outperforming silicon-photonics-based systems. Additionally, the device delivered microjoule-level pulse energies at MHz-level high repetition rates, establishing a new milestone in compact, high-performance waveguide laser architectures.show less