Hua Zhang

Random lasing from Rhodamine 6G doped ethanediol solution based on the cicada wing nanocones

Random lasing from Rhdomaine 6G (Rh6G) doped ethanediol solution based on the cicada wing nanostructures as scatterers has been demonstrated. The optical positive feedback of the random laser is provided by these nanocones on the cicada wing, where the scale of the nanocones and the distance between them is about 150 nm and 200 nm, respectively. Al-coated reflector has been introduced to reduce the loss of the pump energy from the bottom, and moreover lower the laser threshold, which is about 126.0 μJ/pulse. Due to the liquid gain medium, the lifetime of this random laser is longer than conventional random lasers. This random laser shows the potential applications in biological random laser and photonic devices.

Fabrication and Photocatalytic Properties of ZnSe Nanorod Films

ZnSe nanorod films grown on fused quartz glass substrates via a simple two-step synthesis protocol were demonstrated to be environmentally safe and effective recyclable photocatalysts. These films showed greatly enhanced photocatalytic activity compared to pulsed laser deposition ZnSe films in the degradation of methyl orange dye solutions. The well-crystalized ZnSe nanorods had a length of 15 µm and a diameter of 200 nm and were densely grown on the substrate. The morphology, crystal structure, crystal phase, and photophysical properties of the ZnSe nanorod films were investigated using field-emission scanning electron microscopy (FE-SEM), UV-Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HRTEM).

Morphology control and enhancement of 1.5 μm emission in Ca2+/Ce3+ codoped NaGdF4:Yb3+, Er3+ submicrorods

The successful synthesis of rare earth doped nano/microcrystals with the desired morphology, uniform monodispersity, and intense infrared emission is of fundamental significance, and would facilitate their application in infrared emission-related miniaturization and integration in optoelectronics. However, simultaneously controlling the morphology and enhancing the infrared emission through simple and effective methods has not been well explored. In this study, via Ca2+ doping with an optimized concentration of 25 mol% in the hydrothermal solution, irregular NaGdF4:Yb/Er submicrocrystals converted into highly uniform submicrorods. Meanwhile, an obvious enhancement of visible upconversion (UC) and near-infrared (NIR) downconversion (DC) emission were obtained, probably due to the improved morphology and lowering the local crystal field symmetry around the rare earth ions induced by Ca2+ doping. Furthermore, Ce3+ ions with an optimized concentration of 2 mol% were codoped to intentionally tailor the branching ratio through efficient energy transfer from Er3+ to Ce3+. As a result, the ∼1530 nm emission intensity of the NaGdF4: 25Ca/2Ce/20Yb/2Er submicrorods increased by about 6.4 times in comparison with the NaGdF4:20Yb/2Er counterpart.

The effect of the size of Au nanorods on random laser action in a disordered media of ethylene glycol doped with Rh6G dye

Random laser actions in a disordered media based on ethylene glycol doped with Rh6G dye and Au nanorods have been demonstrated. It was observed that the size of Au nanorods strongly affects the pump threshold. The experiment results suggesting that the random lasing properties are dominated by the surface plasmons.

The shape effect of Au particles on random laser action in disordered media of Rh6G dye doped with PMMA polymer

Abstract Random laser actions in a disordered media based on polymethyl methacrylate (PMMA) polymer doped with Rh6G dye and Au nanoparticles have been demonstrated. It was observed that the shape of Au nanoparticles can tune the spectral central position of the random laser action. It was also seen that the shape of Au nanoparticles strongly affects the pump threshold. Comparing nanosphere- and nanorod-based systems, the nanorod-based one exhibited a lower threshold.