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To improve the optical and electrical properties of AlGaN-based deep ultraviolet lasers, an inverse-trapezoidal electron blocking layer is designed. Lasers with three different structural electron blocking layers of rectangular, trapezoidal and inverse-trapezoidal structures are established. The energy band, electron concentration, electron current density, P–I and V–I characteristics, and the photoelectric conversion efficiency of different structural devices are investigated by simulation. The results show that the optical and electrical properties of the inverse-trapezoidal electron blocking layer laser are better than those of rectangular and trapezoidal structures, owing to the effectively suppressed electron leakage.

Molecular dynamics simulations are performed to investigate the effects of low-energy recoils on the microscopic structure of porous silica. Exhibiting a logistic growth with the recoil energy, the displacement probability of Si is shown to be smaller than that of O at the same primary knock-on level. Computations of pair distribution functions and bond angle distributions reveal that this material upon irradiation with energies around the displacement thresholds mainly undergoes structural changes in the medium-range order. In the porous network, while the formation of nonbridging oxygen defects tends to induce shorter Si–O bonds than those formed by bridging oxygen atoms, a remarkable increase of inter-tetrahedral bond angles created by multiple recoils can be observed and associated with the rearrangement of ring statistics.

A double-tapered AlGaN electron blocking layer (EBL) is proposed to apply in a deep ultraviolet semiconductor laser diode. Compared with the inverse double-tapered EBL, the laser with the double-tapered EBL shows a higher slope efficiency, which indicates that effective enhancement in the transportation of electrons and holes is achieved. Particularly, comparisons among the double-tapered EBL, the inverse double-tapered EBL, the single-tapered EBL and the inverse single-tapered EBL show that the double-tapered EBL has the best performance in terms of current leakage.

We propose a coherently prepared three-level atomic medium that can provide a flexible disordered scheme for realizing the Anderson localization. Different disorder levels can be attained by modulating the intensity ratio between the two control beams. Due to the real-time tunability, the localization of the signal beam is observable and controllable. The influences of the induced disorder level, atomic density and the initial waist radius of the signal beam on the Anderson localization in the medium are also discussed.

We show the influences of temperature on the self-imaging in the coherent atomic system which consists of four-level 87Rb atoms. The different-direction self-imaging, the corresponding imaging quality, and the imaging contrast ratio in this Doppler broadening medium are studied. As a result, the imaging-position linearly increases with the temperature, while the quality of the self-imaging does not show clear connection with the temperature. Due to the weaker mutual interference in the higher temperature, the contrast ratios in the two directions increase. The interesting results are important and may have potential applications in imaging storage and processing.

According to density matrix equations of the interaction between light and matter, the expression for the susceptibility of the Eu3+:Y2SiO5 crystal is obtained. When the control field is a Gaussian beam, we investigate and analyze the influence of probe detuning, the Rabi frequency of the control field and the laser line width on the transverse optical properties. We also analyze the influence of the dope-ion concentration on electromagnetically induced transparency (EIT). The analysis result indicates that the transmission is not a monotonic function of the dope-ion concentration. Based on the influences of various parameters on the transverse optical properties, we choose the appropriate parameters to realize the desired EIT and gradient refractive index, which has applications in focusing and imaging.

By means of hybrid density functional theory, we interpret the stability mechanism of the tetragonal CuO phase, which was synthesized using the pulsed laser deposition. The orbital ordering resulted from the crystal field splitting is found to be favorable for the d9 electronic configuration of the Cu2+ ion, yielding two possible metastable tetragonal phases (c/a 1) of CuO. A detailed comparison is also performed with the ideal rock-salt compounds CoO and NiO.

A 2ω wedge design is proposed with KDP crystal to disperse the unconverted light away from the target in a high power laser facility for inertial confinement fusion. The ultraviolet B-integral problem is released, and about 1.2 times in color separation angle is achieved according to both theoretical and experimental investigations when compared with conventional 3ω wedge. The frequency conversion efficiency is unaffected when the wedge is along the non-sensitive axis of the tripler.

The refined topological vertex of Iqbal—Kozcaz—Vafa has been investigated from the viewpoint of the quantum algebra of type W1+∞ by Awata, Feigin, and Shiraishi. They introduced the trivalent intertwining operator Φ which is normal ordered along with some prefactors. We manage to establish formulas from the infinite operator product of the vertex operators and the generalized ones to restore this prefactor, and obtain an explicit formula for the vertex realization of the topological vertex as well as the refined topological vertex.

Temporal, spectral and spatial characters of 0.3-nm-bandwidth high-energy laser pulse propagating through a long path are studied in detail in one newly constructed beamline of our laser facility. The evolution of propagation, pulse energy and near-field deterioration are analyzed theoretically and experimentally. Substituting argon for air is demonstrated effectively to suppress stimulated rotational Raman scattering and the experimental result provides operating criterion, and engineering parameters for the under-constructed beamlines.

We investigate the third-order leader-following consensus problem of nonlinear multi-agent systems in undirected network topologies. Based on graph theory and Lyapunov stability theory, the adaptive control method is employed to achieve leader-following consensus in an undirected network of agents with nonlinear third-order dynamics against the perturbations. Simulation examples validate the correctness of the results and show that the control gains have a great influence on the convergence performance of errors for a short time.

Laser induced damage experiment is carried out on a large aperture laser facility. Severe damage is observed on a large-aperture fused silica grating which presents dense craters on the front surface and six cracks alternatively located at the front and the rear surface. The bizarre fact about the damage on the grating is that, unlike other optics, the damage craters are almost on the front surface. According to observation, damage phenomenon is due to the stimulated Brillouin scattering (SBS) effect occurring in the grating, which includes the transverse SBS, the back SBS and the zigzag SBS.