Hongxing Dong

Single-crystalline tower-like ZnO microrod UV lasers

High quality tower-like ZnO microrods with hexagonal cross-sections were fabricated by a simple reduction–oxidation process. By using the spatially resolved spectroscopic technique, the stable UV lasing was directly observed and further investigated systematically. Our results demonstrated that such tower-like microrods can function as novel cavity based microlasers, which could have potential applications in optoelectronics.

Whispering gallery modes in indium oxide hexagonal microcavities

The work is funded by the NSFC 973 projects and STCSM of China Grant Nos. 2004CB619004 and 2006CB921506. The authors thank the Australian Government Department of Innovation, Industry, Science and Research for funding this collaborative research under the International Science Linkages China Program.

Intense photoluminescence at 2.7 μm in transparent Er 3+ :CaF 2 -fluorophosphate glass microcomposite

Er3+ doped CaF2-fluorophosphate (FP) glass microcomposites were produced by heat-treating the mixture of Er3+:CaF2 precipitate and FP glass powder above the melting temperature of the FP glass. The appearance of CaF2 crystallites in the resulting composites was confirmed by x ray diffraction. Despite the fact that the average diameter of the crystallites was around 10 μm as revealed by the micromorphology study, a transparent composite was obtained by matching the refractive index of FP glass to that of CaF2. Intense IR fluorescence at around 2.7 μm was observed in the composite, implying the composite would be a promising candidate for IR lasers and amplifiers.

Nonlinear Optical Properties of Graphene and Carbon Nanotube Composites

Jun Wang1a, Yu Chen1b, Rihong Li1a, Hongxing Dong1a, Long Zhang1a, Mustafa Lotya2, Jonathan N. Coleman2 and Werner J. Blau2 1aKey Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences 1bKey Laboratory for Advanced Materials, Department of Chemistry, East China University of Science and Technology 2School of Physics and the Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin 1China 2Ireland

Quasi-whispering gallery modes of exciton-polaritons in a ZnO microrod

We report the photoluminescence (PL) investigations of quasi-whispering gallery mode (quasi-WGM) polaritons in a ZnO microrod at room temperature. By using the confocal micro-PL spectroscopic technique, we observe the clear optical quasi-WGMs. These quasi-WGMs appeared in the ultraviolet (UV) emission region where the cavity modes strongly couple with excitons and form polaritons. The quasi-WGMs polaritons can be well described by the plane wave interference and the coupling oscillator model.

On the origin of suppression of free exciton no-phonon emission in ZnO tetrapods

Temperature dependent photoluminescence and cathodoluminescence (CL) spectroscopies are employed to investigate free exciton (FX) emissions in ZnO tetrapods. The intensity of the no-phonon line is ...

Single-crystalline polyhedral In2O3 vertical Fabry–Pérot resonators

High-quality In2O3 polyhedrons with different morphologies were fabricated and studied as vertical Fabry–Perot (FP) microcavities. By using the microphotoluminescence technique, we identified a series of FP resonant modes in such systems, whose energies lie in the visible spectral range and are scalable with the cavity size. Experimental results are in good agreement with full-wave numerical simulations and can be well fitted with a plane wave interference model. Compared with the conventional one dimensional nanowire/nanobelt FP cavities, such vertical FP microcavities have much less optical loss and provide efficient optical modulations, which may find many applications in developing optical devices.

Robust exciton-polariton effect in a ZnO whispering gallery microcavity at high temperature

A robust exciton-polariton effect in a ZnO whispering gallery microcavity well above room temperature is presented. The lower polariton branches are tuned by current induced thermal effect. The red shift can be as large as ∼40 meV. It is found that the strong coupling can be preserved and the polariton-phonon interaction quenching effect remains up to ∼550 K, while the Rabi splitting is about 330 meV. The tuning speed is in the order of millisecond, showing its potential in polariton-based optoelectronic device application.

Thermodynamic-effect-induced growth, optical modulation and UV lasing of hierarchical ZnO Fabry–Pérot resonators

High quality ZnO multilayer hexagonal microplates and microtubes were fabricated via a simple carbothermal method without any catalysts, carrier gases, or low pressure. The formation of the ZnO microstructures with different morphologies was discussed in detail, and a possible thermodynamic viewpoint was proposed. Fabry–Perot (FP) modes and UV lasing were directly observed using a spatially resolved spectroscopic technique. All the resonant modes observed experimentally were identified using finite-difference-time-domain simulations. Excitation power and temperature dependence of lasing properties of the ZnO microplate were further studied. Compared with the conventional one-dimensional nanowire/nanobelt FP cavities, such ZnO multilayer vertical-FP resonators have much less optical loss and excellent optical responses and may find potential applications in UV microlasers.

Two-photon absorption and emission in CsPb(Br/I)3 cesium lead halide perovskite quantum dots

We present the nonlinear optical properties of CsPb(Br/I)3 perovskite quantum dots (QDs) with high crystallinity. The perovskite QDs show better two-photon absorption response than the traditional metal chalcogenide QDs. And, the photoluminescence peak of the halogen vacancies in perovskite nanocrystals was experimentally observed for the first time.