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The aluminum gallium arsenide-on-insulator (AlGaAsOI) platform exhibiting high nonlinearity, strong light confinement, and negligible two-photon absorption (TPA) has motivated research in realizing highly efficient nonlinear devices. Resonator structures can push nonlinear efficiency to unprecedented levels by significantly enhancing the cavity field. In recent years, multimode microring resonators, with lower scattering loss than single-mode designs, have garnered increasing attention for chip-based nonlinear photonics applications. However, the intermodal coupling will degrade the Q and introduce avoided mode crossing (AMX), causing changes in local dispersion. The perturbed dispersion significantly influences the phase-matching condition, making AMX management crucial for multimode resonator design. This paper introduces a fabrication-tolerant tapered waveguide design to achieve selective-mode coupling, enabling single-mode excitation in the bus-ring coupling region and eliminating the unwanted higher-order mode of the multimode waveguide. Leveraging the multimode microring resonators in the AlGaAsOI platform, we demonstrate dark-pulse comb generation through TE00-TE10 mode coupling, and we obtain a large dark pulse existence range of 89 GHz by backward tuning. Moreover, we achieve a widely separated (45 THz) optical parametric oscillation (OPO) with the assistance of higher-order dispersion.

Recent advances in integrated nonlinear material platforms and low-loss optical microresonators enabled a broad range of chip-scale optical applications, such as optical frequency combs, quantum photonics, and optical signal processing. The aluminum gallium arsenide-on-insulator (AlGaAsOI) platform exhibiting high nonlinearity, strong light confinement, and negligible two-photon absorption has motivated research in realizing highly efficient nonlinear components. Low loss and dispersion engineering are essential for nonlinear processes in waveguides as the former allows for a long nonlinear interaction distance while the latter ensures good phase matching. Constructing waveguides into microresonators can bring the nonlinear efficiency of the device to an unprecedented level but also requires extra considerations concerning the excess losses induced by waveguide bend and coupler, and the dispersion perturbation induced by intermodal coupling. This paper presents the fabrication process and its critical aspects for high Q AlGaAsOI microresonators. We report the highest Q for high-confinement III-V microring resonators that are fabricated using an electron-beam lithography-based patterning process. We also present an efficient coupler that simplifies the post-processing step for fiber-chip coupling. Moreover, we present generic design methods to suppress the avoided mode crossing (AMX) or dispersion defects in microresonators and demonstrate AMX-free AlGaAsOI microresonators.

LiMn2O4Doped with Cr2O3spinel cathode materials were coated with Carbon Black (0, 2, 4 wt%). The cathode materials were physically characterized by X-ray diffraction (XRD), Electrochemical impedance spectra (EIS), Cyclic Voltammetry (CV) and Analysis of Charging-discharging. From the XRD analysis, the synthetic materials were spinel structure with a Fd3m space group. From the EIS studies, the coating powers possessed the least impedance and inhibited the Mn dissolution. The CV and Analysis of Charging-discharging indicated the coating improved the performance of large current charge and discharge, the capacity retention and cycle performance.

LiNi0.5Mn1.5O4cathode material was synthesized through sol-gel self-combustion reaction method. LiNi0.5Mn1.5O4powders were subsequently characterized as cathode materials in a Li-ion coin cell comprising a Li anode with electrolyte A or electrolyte B. 1.0 mol/L Lithium Hexafluorophosphate (LiPF6) dissolved in volume ration of ethylene carbonate (EC) to ethyl methyl carbonate (EMC) to diethyl carbonate (DEC) corresponded to 4:3:3as electrolyte A, 1.0 mol/L LiPF6dissolved in volume ration of EC to EMC to DEC corresponded to 4:2:4 as electrolyte B. Electrochemical performance of lithium cells was evaluated. These tests showed that no matter the cells with electrolyte A or electrolyte B has good discharge platform in 4.7V range (3.5V–4.75V) at the rate of 0.1C, the initial discharge capacity of cell with electrolyte B was higher than that with electrolyte A.