Compared with widely established monovalent-ion batteries, aqueous multivalent-ion batteries promise higher capacity release by achieving multiple electron-transfer events per ion intercalation in the host material. Despite plausibility, this high-capacity dream is untenable with the total tolerable redox charge-transfer limit of the host material for all carrier species equally, which is historically assumed to depend on the material rather than the guest carrier itself, and the kinetic hysteresis induced by larger charge/radius ratios induced kinetic hysteresis further enlarges the divide. Herein, we report that copper carrier redox in vanadium sulfide (VS₂) exceeds the intrinsic intercalation capacity boundary, with the highest capacity release as 675 mAh g^-1 at 0.4 A g^-1 among all VS₂ cathodes previously reported. Operando X-ray absorption spectroscopy, operando synchrotron X-ray diffraction and composite ex situ characterization jointly demonstrated that intercalated divalent copper is preferentially involved in redox afforded extra electron transfer to form reversible monovalent copper pillars, thus not only ensuring stable topological de/intercalation with high capacity but also sustaining fast migration kinetic paths through reconfigurable pillar effects. Intercalated carrier redox reported here emphasizes the interlayer variable valence advantage of multivalent ions, providing insights into high-performance multivalent-ion storage chemistry in aqueous batteries.

The miniaturization of optical switches is a promising prospect with the use of phase-change materials (PCMs), and exploring various strategies to effectively integrate PCMs with integrated optical waveguides represents an intriguing research question. In this study, an ultra-compact integrated optical switch based on PCM is proposed. This device consists of a Ge${}_2$Sb${}_2$Te${}_5$ nano-disk and an inverse-designed pixelated sub-wavelength structure. The pixelated sub-wavelength structure offers customized refractive indices that conventional materials or structures cannot achieve, leading to an improved insertion loss (IL) and extinction ratio (ER) performance of the device. Furthermore, this structure enhances the interaction between the optical field and GST, resulting in a reduction of the device size and the inserted GST footprint. With an ultra-compact device footprint of 0.9 µm × 1.5 µm, the simulation results exhibit a low IL of 0.45 dB, and a high ER of 18.0 dB at 1550 nm. Additionally, relevant studies show that this device is able to perform reliably despite minor variations in the manufacturing process.

Inverse design effectively promotes the miniaturization of integrated photonic devices through the modulation of subwavelength structures. Utilizing a theoretical prior based inverse design, we propose an ultra-compact integrated polarizing beam splitter consisting of a standard silicon-on-insulator (SOI) substrate and a tunable air–silicon column two-dimensional code metasurface, with a footprint of 5 × 2.7 μm². The effective refractive index of the waveguide is modulated by adjusting the two-dimensional code morphology in the additional layer to achieve efficient polarization beam splitting. The simulation results demonstrate high performance, with a low insertion loss (10.76 dB) in a bandwidth of 80 nm covering the C-band. The device can withstand manufacturing errors up to ±20 nm and is robust to process defects, such as the outer proximity effect, and thus is suitable for ultra-compact on-chip optical interconnects.

The limited pattern area of periodic nanostructures limits the development of practical devices. This study introduces an X-ray interference lithography (XIL) stitching technique to fabricate a large-area (1.5 cm × 1.5 cm) two-dimensional photonic crystal (PhC) on the YAG: Ce scintillator, which functions as an encoder in a high numerical aperture optical encoding imaging system to effectively capture high-frequency information. An X-ray imaging experiment revealed a substantial 7.64 dB improvement in the signal-to-noise ratio (SNR) across a large field of view (2.6 mm × 2.6 mm) and achieved comparable or superior image quality with half the exposure dose. These findings have significant implications for advancing practical applications of X-ray imaging.

Polarization-insensitive waveguide crossings are indispensable components of photonic integrated circuits (PICs), enabling the concurrent computing of optical signals from diverse waveguides inside the limits of a restricted spatial footprint. Leveraging mirror symmetry direct binary search, we successfully demonstrate an ultra-compact and ultra-low loss polarization-insensitive waveguide crossing that achieves insertion losses below −0.11 dB and crosstalk levels beneath −22.6 dB for transverse electric (TE) mode, as well as insertion losses below 0.05 dB and crosstalk levels beneath −24.5 dB for transverse magnetic (TM) mode across the C-band with a footprint of 3 × 4 μm². The results confirm that this mirror symmetry optimization method yields high-efficiency devices while reducing computational time. We believe this high-efficiency polarization-insensitive waveguide crossing can have potential applications in dense PIC systems.

Utilization of phase change material in integrated photonic switches has gained significant attention due to its benefits of a broader bandwidth, higher switching contrast, smaller footprint, lower energy consumption, and better structural stability. In this paper, we propose an ultra-compact integrated photonic switch that utilizes a Ge₂Sb₂Se₄Te₁ (GSST) nanodisk with a diameter of 440 nm inserted into a slot waveguide on a standard silicon on insulator, with a footprint of only 2.8×0.66µm². A meta-structure mode conversion element is also proposed to be used in series with the slot GSST switch. Simulations of the photonic switch show that the insertion loss of the device during the “ON” state is below 0.564 dB, and the extinction ratio is above 12.846 dB over a large wavelength of 1210 to 1410 nm (covering the entire O band), with a peak value of 16.694 dB. The proposed photonic switch will find potential in various applications in optical communication systems and optical networks.