High-bandwidth and low-loss photonic crystal power-splitter with parallel output based on the integration of Y-junction and waveguide bends

A 1×2 power-splitter with parallel output that exhibits high-bandwidth and low-loss splitting for TE-polarized light is designed based on a photonic crystal slab in a silicon-on-insulator (SOI) material. The high performance is achieved by the integration of a Y-junction and 60° waveguide bends, which is designed to ensure single-mode operation, and keep the output channels of the power-splitter be parallel to the input channel. With a three-dimensional finite-difference time-domain (3D-FDTD) technique, ultralow-loss output of the optimized power-splitter with normalized transmission above 45% (in the range 3.216±0.18 dB) is obtained in the high-bandwidth range 1472–1634 nm, which covers the entire C-band of optical communication. In addition, the simulation results demonstrate that when the manufacture error of the lattice shift (dx) is in the range of ±10 nm, the disturbance of the transmission and the bandwidth are 1.52% and 6.79%, respectively. Both the specific result and the general idea of integration design are promising in the optical integrated circuit (OIC) and integrated optical devices in the future.     

Electroactive Metal–Organic Frameworks as Emitters for Self-Enhanced Electrochemiluminescence in Aqueous Medium

Metal–organic frameworks (MOFs) have limited applications in electrochemistry owing to their poor conductivity. Now, an electroactive MOF (E-MOF) is designed as a highly crystallized electrochemiluminescence (ECL) emitter in aqueous medium. The E-MOF contains mixed ligands of hydroquinone and phenanthroline as oxidative and reductive couples, respectively. E-MOFs demonstrate excellent performance with surface state model in both co-reactant and annihilation ECL in aqueous medium. Compared with the individual components, E-MOFs significantly improve the ECL emission due to the framework structure. The self-enhanced ECL emission with high stability is realized by the accumulation of MOF cation radicals via pre-reduction electrolysis. The self-enhanced mechanism is theoretically identified by DFT. The mixed-ligand E-MOFs provide a proof of concept using molecular crystalline materials as new ECL emitters for fundamental mechanism studies.     

A review of enantioselective dual transition metal/photoredox catalysis

Transition metal catalysis is one of the most important tools to construct carbon-carbon and carbon-heteroatom bonds in modern organic synthesis. Visible-light photoredox catalysis has recently drawn considerable attention of the scientific community owing to its unique activation modes and significance for the green synthesis. The merger of photoredox catalysis with transition metal catalysts, termed metallaphotoredox catalysis, has become a popular strategy for expanding the synthetic utility of visiblelight photocatalysis. This strategy has led to the discovery of novel asymmetric transformations, which are unfeasible or not easily accessible by a single catalytic system. This contemporary area of organic chemistry holds promise for the development of economical and environmentally friendly methods for the asymmetric synthesis of chiral compounds. In this review, the advances in the enantioselective metallaphotoredox catalysis(EMPC) are summarized.     

Hydrogenation of acetylene into ethane–ethene mixtures over modified Pd–alumina catalysts

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Reversal of circularly polarized luminescence direction and an “on-off” switch driven by exchange between UV light irradiation and the applied direct current electric field

Science China Chemistry - We report the rational design of a dual stimulus-activated quaternary chiral emission nematic liquid crystals (Q-N*-LCs) containing light-driven chiral dopant R-S-R-1, a...