PhotoniX最新文献

Since the concept of adaptive optics(AO) was proposed in 1953, AO has become an indispensable technology for large aperture ground-based optical telescopes aimed at high resolution observations. This paper provides a comprehensive review of AO progress for large aperture astronomical optical telescopes including both night-time and day-time solar optical telescopes. The recent AO technological advances, such as Laser Guide Star, Deformable Secondary Mirror, Extreme AO, and Multi-Conjugate AO are focused.

Optical encryption plays an increasingly important role in the field of information security owing to its parallel processing capability and low power consumption. Employing the ultrathin metasurfaces in optical encryption has promoted the miniaturization and multifunctionality of encryption systems. Nevertheless, with the few number of degrees of freedom (DoFs) multiplexed by single metasurface, both key space and encoding space are limited. To address this issue, we propose a high-security and large-capacity optical encryption scheme based on perfect high-dimensional Poincaré beams with expanded DoFs. By cascading two arrayed metasurfaces, more beam properties can be independently engineered, which gives rise to the extensively expanded key and encoding spaces. Our work provides a promising strategy for optical encryption with high security level and large information capacity and might facilitate the applications of Poincaré beams in optical communications and quantum information.

The molecular fingerprint sensing technology based on metasurface has unique attraction in the biomedical field. However, in the terahertz (THz) band, existing metasurface designs based on multi-pixel or angle multiplexing usually require more analyte amount or possess a narrower tuning bandwidth. Here, we propose a novel single-pixel graphene metasurface. Based on the synchronous voltage tuning, this metasurface enables ultra-wideband ((sim) 1.5 THz) fingerprint enhancement sensing of trace analytes, including chiral optical isomers, with a limit of detection (LoD) ≤ 0.64 μg/mm². The enhancement of the fingerprint signal ((sim) 17.4 dB) originates from the electromagnetically induced transparency (EIT) effect excited by the metasurface, and the ideal overlap between the light field constrained by single-layer graphene (SLG) and ultra-thin analyte. Meanwhile, due to the unique nonlinear enhancement mechanism in graphene tuning, the absorption envelope distortion is inevitable. To solve this problem, a universal fingerprint spectrum inversion model is developed for the first time, and the restoration of standard fingerprints reaches R_max² ≥ 0.99. In addition, the asynchronous voltage tuning of the metasurface provides an opportunity for realizing the dynamic reconfiguration of EIT resonance and the slow light modulation in the broadband range. This work builds a bridge for ultra-wideband THz fingerprint sensing of trace analytes, and has potential applications in active spatial light modulators, slow light devices and dynamic imaging equipments.

Optical imaging techniques provide low-cost, non-radiative images with high spatiotemporal resolution, making them advantageous for long-term dynamic observation of blood perfusion in stroke research and other brain studies compared to non-optical methods. However, high-resolution imaging in optical microscopy fundamentally requires a tight optical focus, and thus a limited depth of field (DOF). Consequently, large-scale, non-stitched, high-resolution images of curved surfaces, like brains, are difficult to acquire without z-axis scanning. To overcome this limitation, we developed a needle-shaped beam optical coherence tomography angiography (NB-OCTA) system, and for the first time, achieved a volumetric resolution of less than 8 μm in a non-stitched volume space of 6.4 mm × 4 mm × 620 μm in vivo. This system captures the distribution of blood vessels at 3.4-times larger depths than normal OCTA equipped with a Gaussian beam (GB-OCTA). We then employed NB-OCTA to perform long-term observation of cortical blood perfusion after stroke in vivo, and quantitatively analyzed the vessel area density (VAD) and the diameters of representative vessels in different regions over 10 days, revealing different spatiotemporal dynamics in the acute, sub-acute and chronic phase of post-ischemic revascularization. Benefiting from our NB-OCTA, we revealed that the recovery process is not only the result of spontaneous reperfusion, but also the formation of new vessels. This study provides visual and mechanistic insights into strokes and helps to deepen our understanding of the spontaneous response of brain after stroke.

Aqueous zinc-ion batteries provide a most promising alternative to the existing lithium-ion batteries due to their high theoretical capacity, intrinsic safety, and low cost. However, commercializing aqueous zinc-ion batteries suffer from dendritic growth and side reactions on the surface of metallic zinc, resulting in poor reversibility. To overcome this critical challenge, here, we report a one-step ultrafast laser processing method for fabricating three-dimensional micro-/nanostructures on zinc anodes to optimize zinc nucleation and deposition processes. It is demonstrated that the three-dimensional micro-/nanostructure with increased specific surface area significantly reduces nucleation overpotential, as well as preferentially absorbs zinc ions to prevent dendritic protuberances and corrosion. As a result, the presence of three-dimensional micro-/nanostructures on the zinc metal delivers stable zinc plating/stripping beyond 2500 h (2 mA cm^-2/1 mAh cm^-2) in symmetric cells, a high Coulombic efficiency (99.71%) in half cells, and moreover an improved capacity retention (71.8%) is also observed in full cells. Equally intriguingly, the pouch cell with three-dimensional micro-/nanostructures can operate across various bending states without severely compromising performance. This work provides an effective strategy to construct ultrafine and high-precision three-dimensional micro-/nanostructures achieving high-performance zinc metal anodes and is expected to be of immediate benefit to other metal-based electrodes.