Two-dimensional (2D) all-inorganic halide perovskites exhibit promise for optoelectronic applications, yet selective exfoliation along specific crystallographic planes remains a critical challenge for performance optimization. Using first-principles calculations combined with device simulations, we systematically investigated the structural stability, exfoliation feasibility, and optoelectronic properties of 24 all-inorganic 2D perovskites derived from the (100) and (111) planes of cubic perovskites, specifically the A2BX4 and A3B′2X9 series (A = Cs, Rb; B = Pb, Sn; B′ = Bi, Sb; X = Cl, Br, I). Our results demonstrate that (111)-derived A3B′2X9 perovskites exhibit significantly lower exfoliation energies (23.1−62.1 meV/Å2) than (100)-derived A2BX4 counterparts (59.7−174.0 meV/Å2), attributed to weaker van der Waals interlayer coupling in the former. Rb3Bi2I9 possesses an ultralow exfoliation energy of 23.1 meV/Å2, rivaling that of graphene and demonstrating exceptional potential for mechanical exfoliation of high-quality monolayers. A2BX4 monolayers exhibit direct band gaps, which are favorable for optoelectronic applications; whereas A3B′2X9 monolayers display indirect band gaps. Among all investigated materials, monolayer Rb2SnBr4 emerges as an outstanding candidate, featuring an ideal direct band gap of 1.34 eV (HSE06) that perfectly matches the Shockley−Queisser limit for single-junction solar cells. SCAPS-1D device simulations further predict that optimized Rb2SnBr4-based solar cells can achieve a remarkable theoretical power conversion efficiency of 27.10% under defect densities below 1014 cm−3. This work establishes that (111) plane cleavage is optimal for synthesizing exfoliable 2D perovskites, while (100) plane orientation enables superior direct band gap characteristics for photovoltaic applications, providing critical design principles for crystallographic plane engineering in halide perovskite devices.

Kerr resonator is one of the most popular platforms to produce optical frequency comb and temporal cavity soliton. As an essential method for investigating the nonlinear dynamics of Kerr resonators, traditional numerical simulations rely on solving the Lugiato-Lefever equation (LLE) using the split-step Fourier method (SSFM), which is computationally intensive and time-consuming. To address this challenge, this study proposes a recurrent neural network model with prior information feedback, enabling efficient and accurate prediction of soliton dynamics in Kerr resonator. With the acceleration of graphics processing unit (GPU), the computational efficiency improved by 20 times. We compared various recurrent neural networks and found that the gated recurrent unit (GRU) network demonstrated superior performance in this task. This work highlights the potential of artificial intelligence (AI) for modeling nonlinear optical dynamics in Kerr resonator, paving the way for designing optical frequency comb and generating ultrafast pulse.

This study explores the application of cold plate liquid cooling technology in co-packaged optics (CPO). By integrating optical modules and the switch chip on the same substrate, CPO shortens the electrical interconnection distance, effectively solving the problems of high power consumption and poor signal integrity of traditional pluggable optical modules under high bandwidth. However, the surge in power density and the thermal crosstalk resulting from high integration density make thermal management one of the key challenges that constrain the reliability of high-capacity co-packaged optics. For the unique architecture of CPO, this study analyzes its heat dissipation needs in detail, and a thermal management scheme is designed. The thermal management scheme is simulated and optimized based on the Navier−Stokes equation. The simulation results show that, in a 51.2 Tbit/s CPO system, the junction temperature of the switch chip is 97.3 °C, the maximum junction temperature of the optical modules is 31.3 °C, and the temperature difference between the optical modules is 2.4 °C to 1.2 °C. To verify the simulation results, a thermal test experimental platform is built, and the experimental results show that the temperature simulation difference is within 4% and the pressure change trend is consistent with the simulation. Combining the experimental data and simulation results, the designed heat sink can satisfy the heat dissipation demands of the 51.2 Tbit/s bandwidth CPO system. This conclusion demonstrates the potential of liquid-cooling technology in CPO, providing support for research on liquid-cooling technology in the CPO. The design provides a theoretical and practical basis for the high performance and reliability of optoelectronic integration technology in wavelength division multiplexing (WDM) systems and micro-ring device applications, contributing to the application of next-generation optical communication networks.Graphical

The progressive number of old adults with cognitive impairment worldwide and the lack of effective pharmacologic therapies require the development of non-pharmacologic strategies. The photobiomodulation (PBM) is a promising method in prevention of early or mild age-related cognitive impairments. However, it remains unclear the efficacy of PBM for old patients with significant age-related cognitive dysfunction. In our study on male mice, we show a gradual increase in the brain amyloid beta (Aβ) levels and a decrease in brain drainage with age, which, however, is associated with a decline in cognitive function only in old (24 months of age) mice but not in middle-aged (12 months of age) and young (3 month of age) animals. These age-related features are accompanied by the development of hyperplasia of the meningeal lymphatic vessels (MLVs) in old mice underlying the decrease in brain drainage. PBM improves cognitive training exercises and Aβ clearance only in young and middle-aged mice, while old animals are not sensitive to PBM. These results clearly demonstrate that the PBM effects on cognitive function are correlated with age-mediated changes in the MLV network and may be effective if the MLV function is preserved. These findings expand fundamental knowledge about age differences in the effectiveness of PBM for improvement of cognitive functions and Aβ clearance as well as about the lymphatic mechanisms responsible for age decline in sensitivity to the therapeutic PBM effects.Graphical

Cost-effective soft imprint lithography technique is used to prepare flexible thin polymeric surfaces containing a periodic arrangement of nanodimples and nanobumps of sub-micron size. Using a single master mold of self-assembled colloidal crystal, metasurfaces with different depths and heights of patterns with a fixed pitch are possible, which makes the process inexpensive and simple. These metasurfaces are studied for their diffuse and total transmission and reflection spectra in the visible range. The transmission haze and reflection haze are calculated from the measurements. The surface containing nanobumps of lesser pattern height result in higher values of reflection and transmission haze than from surfaces containing nanodimples of much higher depth for the same pitch. The haze is more dependent on the pattern depth or height and less dependent on the pitch of the pattern. Far-field transmission profiles measured in the same wavelength range from the patterned surfaces show that the scattering increases with the increase of the ratio of pattern depth/height to pitch, similar to the haze measurements conducted with a closed integrating sphere. These profiles show that the angular spread of scattered light in transmission is within 10°, explaining the reason for the relatively low transmission haze in all the patterned surfaces. Simulation results confirm that the nanobump pattern gives higher transmission haze compared to nanodimple pattern. By controlling the ratio of pattern depth/height to pitch of the features on these surfaces, both an increase in optical haze and a balance between total reflection intensity and total transmission intensity can be achieved.Graphical

Novel poly(dimethylsiloxane) (PDMS) doped with two different spiropyran derivatives (SP) were investigated as potential candidates for the preparation of elastomeric waveguides with UV-dependent optical properties. First, free-standing films were prepared and evaluated with respect to their photochromic response to UV irradiation. Kinetics, reversibility as well as photofatigue and refractive index of the SP-doped PDMS samples were assessed. Second, SP-doped PDMS waveguides were fabricated and tested as UV sensors by monitoring changes in the transmitted optical power of a visible laser (633 nm). UV sensing was successfully demonstrated by doping PDMS using one spiropyran derivative whose propagation loss was measured as 1.04 dB/cm at 633 nm, and sensitivity estimated at 115% change in transmitted optical power per unit change in UV dose. The decay and recovery time constants were measured at 42 and 107 s, respectively, with an average UV saturation dose of 0.4 J/cm2. The prepared waveguides exhibited a reversible and consistent response even under bending. The sensor parameters can be tailored by varying the waveguide length up to 21 cm, and are affected by white light and temperatures up to 70 ℃. This work is relevant to elastomeric optics, smart optical materials, and polymer optical waveguide sensors.Graphical

The multiple absorber layer perovskite solar cells (PSCs) with charge transport layers-free (CTLs-free) have drawn widespread research interest due to their simplified architecture and promising photoelectric characteristics. Under the circumstances, the novel design of CTLs-free inversion PSCs with stable and nontoxic three absorber layers (triple Cs3Bi2I9, single MASnI3, double Cs2TiBr6) as optical-harvester has been numerically simulated by utilizing wxAMPS simulation software and achieved high power conversion efficiency (PCE) of 14.8834%. This is owing to the innovative architecture of PSCs favors efficient transport and extraction of more holes and the slender band gap MASnI3 extends the absorption spectrum to the near-infrared periphery compared with the two absorber layers architecture of PSCs. Moreover, the performance of the device with p-type-Cs3Bi2I9/p-type-MASnI3/n-type-Cs2TiBr6 architecture is superior to the one with the p-type-Cs3Bi2I9/n-type-MASnI3/n-type-Cs2TiBr6 architecture due to less carrier recombination and higher carrier life time inside the absorber layers. The simulation results reveal that Cs2TiF6 double perovskite material stands out as the best alternative. Additionally, an excellent PCE of 21.4530% can be obtained with the thicker MASnI3 absorber layer thickness (0.4 µm). Lastly, the highest-performance photovoltaic devices (28.6193%) can be created with the optimized perovskite doping density of around E15 cm3 (Cs3Bi2I9), E18 cm3 (MASnI3), and 1.5E19 cm3 (Cs2TiBr6). This work manifests that the proposed CTLs-free PSCs with multi-absorber layers shall be a relevant reference for forward applications in electro-optical and optoelectronic devices.Graphical

In this paper, we report a coherent beam combining (CBC) system that involves two thulium-doped all-polarization maintaining (PM) fiber chirped pulse amplifiers. Through phase-locking the two channels via a fiber stretcher by using the stochastic parallel gradient descent (SPGD) algorithm, a maximum average power of 265 W is obtained, with a CBC efficiency of 81% and a residual phase error of λ/17. After de-chirping by a pair of diffraction gratings, the duration of the combined laser pulse is compressed to 690 fs. Taking into account the compression efficiency of 90% and the main peak energy proportion of 91%, the corresponding peak power is calculated to be 4 MW. The laser noise characteristics before and after CBC are examined, and the results indicate that the CBC would degrade the low frequency relative intensity noise (RIN), of which the integration is 1.74% in [100 Hz, 2 MHz] at the maximum combined output power. In addition, the effects of the nonlinear spectrum broadening during chirped pulse amplification on the CBC efficiency are also investigated, showing that a higher extent of pulse stretching is effective in alleviating the spectrum broadening and realizing a higher output power with decent combining efficiency.Graphical

The topological photonics plays an important role in the fields of fundamental physics and photonic devices. The traditional method of designing topological system is based on the momentum space, which is not a direct and convenient way to grasp the topological properties, especially for the perturbative structures or coupled systems. Here, we propose an interdisciplinary approach to study the topological systems in real space through combining the information entropy and topological photonics. As a proof of concept, the Kagome model has been analyzed with information entropy. We reveal that the bandgap closing does not correspond to the topological edge state disappearing. This method can be used to identify the topological phase conveniently and directly, even the systems with perturbations or couplings. As a promotional validation, Su–Schrieffer–Heeger model and the valley-Hall photonic crystal have also been studied based on the information entropy method. This work provides a method to study topological photonic phase based on information theory, and brings inspiration to analyze the physical properties by taking advantage of interdisciplinarity.Graphical