With the progress of wide bandgap semiconductors, compact solid-state light-emitting devices for the ultraviolet wavelength region are of considerable technological interest as alternatives to conventional ultraviolet lamps in recent years. Here, the potential of aluminum nitride (AlN) as an ultraviolet luminescent material was studied. An ultraviolet light-emitting device, equipped with a carbon nanotube (CNT) array as the field-emission excitation source and AlN thin film as cathodoluminescent material, was fabricated. In operation, square high-voltage pulses with a 100 Hz repetition frequency and a 10% duty ratio were applied to the anode. The output spectra reveal a dominant ultraviolet emission at 330 nm with a short-wavelength shoulder at 285 nm, which increases with the anode driving voltage. This work has explored the potential of AlN thin film as a cathodoluminescent material and provides a platform for investigating other ultrawide bandgap (UWBG) semiconductors. Furthermore, while using AlN thin film and a carbon nanotube array as electrodes, this ultraviolet cathodoluminescent device can be more compact and versatile than conventional lamps. It is anticipated to be useful in a variety of applications such as photochemistry, biotechnology and optoelectronics devices.

The competition characteristics of different orders of whispering-gallery lasing modes in a single ZnO microwire with hexagonal cavity are investigated comprehensively. As the scale of the cavity increases, the mode competition would be emerging strongly. The high-order whispering-gallery mode (WGM) lasing is indicated to be transverse electric modes with polarization dependence of about 86%. In addition, the competition of whispering-gallery lasing modes depends strongly on the diameter of cavities and the excitation intensities due to the effects of spatial hole burning. The Power Fourier transfer gives the distinct path length of fundamental and high-order optical field. Moreover, the finite difference time domain presents the optical field of high-order WGM lasing that tends to be closer to the center of hexagonal cavities. Remarkably, the Purcell factors of WGM are enhanced strongly with the reduction in diameter of hexagonal cavities, and the maximum value of F p approaches 20.

Robust polariton in the strong‐coupling regime plays a central role in understanding Bose–Einstein condensation (BEC), which is also an ideal platform for the simulation of bosonization processes and novel engineering polariton devices that are related to quantum phase transitions. A two‐dimensional ZnO nanoplate is firstly utilized to construct microcavity polaritons, and a robust polariton BEC laser is successfully realized at room temperature (RT). High stability of the exciton state and the enhanced coupling strength in the nanoplate cavity are effective for polaritons. The giant Rabi splitting of 120 meV is extracted from the RT dispersion pattern. The evolution of polariton BEC exhibits a typical blue‐shift, and its saturation behavior shows that the interaction strength of the polaritons is deduced from the energy renormalization. Remarkably, the value of the interaction strength is two orders of magnitude higher than reported values, which implies that many‐body correlation may be dominant in the polariton strongly interacting polariton systems. The results open up the prospect of realizing robust polariton BEC lasers at high temperature.

In the progress of nanoengineering of noble metals, the extreme nonlinear optics within nanometric volumes is of great research interest in recent years. In particular, plasmonic nanostructures offer unique route for enhancing high-order harmonic generation and other nonlinear optical progress. Here, we report that strong third harmonic emission in zinc oxide (ZnO) microbelts via a strong localization of electromagnetic field caused by localized surface plasmon (LSP) resonances. In MB/Au-nanoparticles composite, it was demonstrated that the intensity of third-harmonic generation (THG) was enhanced by a factor of five compared to bare microbelt (MB). Additionally, the polarization characteristics of THG in the same system were illustrated in detail. With respect to the bare MB, the polarization degree of THG was improved significantly. The nonlinear polarization features can be attributed to the crystal structure and the ensemble of anisotropic plasmonic hot spots on the surface of Au nanoparticles. Finally, intrinsic enhancement process of THG was explored comprehensively by finite difference time domain (FDTD) method. The simulation results are consistent with our experimental observation.

We report observation of dispersion for coupled exciton-polariton in a plate microcavity combining with ZnO/MgZnO multi-quantum well (QW) at room temperature. Benefited from the large exciton binding energy and giant oscillator strength, the room-temperature Rabi splitting energy can be enhanced to be as large as 60 meV. The results of excitonic polariton dispersion can be well described using the coupling wave model. It is demonstrated that mode modification between polariton branches allowing, just by controlling the pumping location, to tune the photonic fraction in the different detuning can be investigated comprehensively. Our results present a direct observation of the exciton-polariton dispersions based on two-dimensional oxide semiconductor quantum wells, thus provide a feasible road for coupling of exciton with photon and pave the way for realizing novel polariton-type optoelectronic devices.