Numerical simulation of end-pumped CW Nd^(3+):GdVO_4 laser at 1063nm

A theoretical model to simulate an end-pumped CW Nd^3＋：GdVO4 laser at 1063 nm is presented. Its essence is to use the propagation equations to demonstrate the spatial evolutions of the pump and the laser powers in the cavity, hence it is applicable to both low and high gain lasers. The simulation results obtained by this model are in good agreement with the experimental observations reported in the literature for a Ti：sapphlre-pumped Nd^3＋：GdVO4 laser. Moreover, some parameters, such as the reflectivity of output coupler, the spot size of laser beam and the crystal length, are discussed with a view to optimizing the laser performance.

Simulation of Thermal Stress in a CW End-Pumped A-Cut Nd：YV04 Crystal

In this research, numerical simulation and experimental results of thermal stress due to an end-pumped Nd：YVO4 a-cut crystal with 0.5% Nd doping were compared. The findings demonstrate a good consistency with experiment. As in this paper has been predicted, at the pumping power above 23 watt, thermal stress has been bigger than thermal facture limit and crystal has broken.

Deriving Energy-Level Gap of a System in Presence of a Kerr-like Medium by Virtue of Invariant Eigen-operator Method

In this paper, we find the invariant eigen-operators （IEOs） and the energy-level gap of a system with a two-level atom interacting with single mode cavity field through multi-photon transition in the presence of a Kerr-like medium. From this work, one can see that the IEO method in many eases is simpler and easier on obtaining the energy-level gap formula than the usual way.

Temperature dependence of the energy-level shift induced by the Bose-Einstein condensation of photons

We investigate the energy-level shift of a hydrogen atom in a two-dimensional optical microcavity, where there exists a Bose-Einstein condensation of photons. It is found that below the critical temperature Tc, the energy-level shift of the bound electron is dependent on temperature, and it is a monotonically increasing function of the absolute temperature T. Especially, at the absolute zero temperature, the energy-level shift entirely comes from the Lamb shift, and the atom can be treated approximately, that is, in vacuum.

Transverse mode transition and LG_(01)-mode generation in an end-pumped Nd:YVO_4 laser

A laser-diode end-pumped Nd：YVO4 crystal laser is demonstrated to emit the first-order Laguerre- Gaussian （LGm） mode with 502-mW laser power and 22% slope efficiency. Tile LGm-mode is lased only when the pumping area locates in the central part of the laser crystal＇s front surface, and thereafter the symmetrical LGm-HGol-TEM00 mode transition happens when laser crystal is moved laterally inside several-tens-micron area. The possible mechanism responsible for the phenomenon of symmetrical mode transition is also discussed.

Simultaneous all-solid-state multi-wavelength lasers——a promising pump source for generating highly coherent terahertz waves

A diode-end-pumped Nd：YAG dual-wavelength laser operating at 1319 and 1338 nm is demonstrated. The maximum average output power of the quasi-continuous wave linearly polarized dual-wavelength laser is obtained to be 2.1 W at a repetition rate of 50 kHz with an output power instability of less than 0.38% and beam quality factor M^2 of 1.45. Using the two lines, the highly coherent and narrow linewidth terahertz radiation of 3.23 THz can be generated in an organic 4-N, N-dimethylamino-methyl-stilbazolium tosylate （DAST） crystal. Meanwhile, the multi-wavelength red laser at 659.5, 664 and 669 nm is generated by frequency doubling and sum frequency processes in a lithium triborate （LBO） crystal. The average red laser output power is enhanced up to 1.625 W at a repetition rate of 15 kHz with an output power instability of better than 0.53% and beam quality factor M^2 of 6.05. Using the three lines, it is possible to generate the multi-wavelength THz radiation of 3.3, 3.43 and 6.73 THz in an appropriate difference frequency crystal.

Generation of Laguerre-Gaussian beam from end-pumped and c-cut Nd:YVO_4 laser

We demonstrate an end-pumped, c-cut Nd：YVO4 laser that emitted first-order Laguerre-Gaussian （LGol） beam by adjusting the position of focused pump beam relative to laser crystal. The pumping light reached the laser crystal has circular and solid intensity profile. The laser is compact and stable, and the obtained LG01 beam power reaches 202 mW with -25% slope efficiency.

Novel Understanding of Electron States Architecture and Its Dimensionality in Semiconductors

Some important insights into the electron-states-architecture (ESA) and its dimensionality (from 3 to 0) in a semiconductor (or generally crystalline) material are obtained. The self-consistency of the set of density of states (DOS) expressions with different dimensionalities is remediated through the clarification and rearrangement of the wave-function boundary conditions for working out the eigenvalues in the wave vector space. The actually too roughly observed and theoretically unpredicted critical points for the dimensionality transitions referring to the integer ones are revealed upon an unusual assumption of the intrinsic energy-level dispersion (ELD). The ELD based quantitative physical model had been established on an immediate instinct at the very beginning and has been properly modified afterwards. The uncertainty regarding the relationship between the de Broglie wavelength of electrons and the dimensionality transitions, seeming somewhat mysterious before, is consequentially eliminated. The effect of the material dimensions on the ELD width is also predicted and has been included in the model. The continuous evolution of the ESA dimensionality is convincingly and comprehensively interpreted and thus the area of the fractional ESA dimensionalities is opened. Another new assumption of the spatial extension shrinkage (SES) closely related to the ELD has also been made and thus the understanding of the behavior of an electron or, in a general sense, a particle has become more comprehensive. This work would manifest itself a new basis for further development of nanoheterostructures (or low dimensional heterostructures including the quantum wells, quantum wires, quantum dots and especially the hetero-dimensional structures). Expected should also be the possible inventions of some novel electronic and optoelectronic devices. More basically, it leads to a new quantum mechanical picture, the essential modifications of Schrödinger equation and Newtonian equation that give rise to a full cosmic-scope picture, and a super-low-speed relativity assumption.

Pseudo-invariant Eigen-Operator Method for Solving Field-Intensity-Dependent Jaynes-Cummings Model

By using Gumming （JC） model. energy-level gap of this the pseudo invariant eigen-operator method we The pseudo-invariant eigen-operator is found in JC Hamiltonian is derived. This approach seems analyze the field-intensity-dependent Jaynes terms of the supersymmetric generators. The concise.

Fine-Structure Splittings of Nitrogen Isoelectronic Sequence： Competitions among Spin-Orbit Interactions, Breit Interactions and Electron Correlations

Using the multi-configuration Dirac-Fock self-consistent field method and the relativistic configuration interaction method with quantum-electrodynamics corrections performed by the GRASP code, we calculate the fine-structure energy levels of the ground-state configuration （1s^22s^22p^3） of the nitrogen isoelectronic sequence, according to the L-S coupling scheme with atomic number Z up to 22. Based on the calculated results, we elucidate the mechanism of the orderings of fine-structure energy levels of 2^ D3/2,5/2 and 2^P1/2,3/2 respectively, i.e. for 2^D3/2,5/2 orderings, the competition between the spin-orbit interactions and the Breit interactions; for 2^P1/2,3/2 orderings, the electron correlations, especially the electron correlations owing to the 2p^5 configuration interactions.

Design and Optimization of Communication System Based on Superconducting Three-Energy-Level System

We propose aΛ-type superconducting three-energy-level device-based communication system for extremely weak microwave communication scenarios,for example,long-distance deep-space communication.We provide a system diagram and propose the frame synchronization and power estimation approaches based on pre-defined synchronization sequences.Based on the microwave response characteristics of the superconducting three-energy-level system,we further investigate the optimization of synchronization sequence and information symbol modulation.We show that three-energy-level systems with weak Markovianity can be approximated using independent identical distribution methods to obtain optimal synchronization sequences,and the optimal modulation is asymmetric.The proposed system design and optimization approaches are evaluated by numerical results.Moreover,we investigate the performance of the three-energy-level communication system in the presence of interference.Simulation results show that the three-energy-level communication system can tolerate more than 10 dB interference compared to long term evolution(LTE)systems and achieve the same communication rate for the same bandwidth and temperature.

Chiral doublet bands and energy-level crossing

Different definitions for chiral doublet bands based on excitation energies, B(E2) and B(M1) respectively are discussed in the triaxial particle rotor model. For the ideal chiral geometry, the selection rules of the electromagnetic transitions in different band definitions are illustrated. It is also shown that the energy-level crossings between chiral doublet bands may occur.

The Landau-level structure of a single polaron in a nanorod under a non-uniform magnetic field

Nanorod is a unique low-dimensional nanometer structure in which the Landau level arrangement of polaron is essential for understanding its quasiparticle system. However, the stability of the polaron level is susceptible to external factors, such as changing magnetic fields.In this manuscript, the Pekar variational method is employed to calculate the external magnetic field's effect on the nanorod's polaron Landau level. It was found that different magnetic fields have different effects on the polaron energy levels of the nanorod, which demonstrated that the external environment had critical effects on the polaron energy levels. This study provides a theoretical basis for regulating the interaction between electrons and phonons in low-dimensional nanomaterials.

The Origin of Multi-Peak Structures Observed in Photoluminescence Spectra of InAs/GaAs Quantum Dots

Multi-peak structures in photoluminescence spectra of InAs/GaAs quantum dots are investigated. Excitation power-dependent photoluminescence spectra are used to identify the nature of different peaks. By combining experimental results and an energy-level structure analysis,origins of the multi-peaks are identified. Furthermore,inter-subband spacing of electrons and holes are deduced.

Crystal-chemistry insight into the photocatalytic activity of BiOCI_(x)Br_(1_x)nanoplate solid solutions

In this study,a facile alcoholysis method was developed to synthesize BiOCI_(x)Br_(1_x)nanoplates at room temperature and atmospheric pressure.In this route,strong acid or alkaline environment was absolutely avoided to realize the high exposure of{001}crystal facets.The regular changes in XRD peaks and cell parameters as a function of the Br content strongly declared that the obtained BiOCIxBrl_x products belonged to a group of solid solutions.The 2D nanosheets with in-plane wrinkles were clearly observed in TEM images.Interestingly,as the Br content increased,band gaps of BiOCI_(x)Br_(1_x)solid solutions gradually decreased.The photocatalytic degradation of RhB under simulated sunlight irradiation indicated that BiOCI0.sBr0.5 had the best photocatalytic activity.From the viewpoint of crystal chemistry,the photocatalytic activity of BiOCI_(x)Br_(1_x)solid solutions was closely related with the exposure amount of{001}facets,interlayer spacing of(001)plane and energy-level position of valence band.

Comparison of energy structure and spectral properties of Ce:LaAlO_3 and Ce:Lu_2(SiO_4)O

Undoped LaAlO3 and 1 at.%Ce:LaAlO3 single crystals were grown by the Czochralski process.Absorption and fluorescence spectra were measured at room temperature.Detailed energy levels structure of Ce:LaAlO3 was determined.In this paper,two viewpoints were provided.The first one is:the energy levels structure of Ce:LaAlO3 is very similar to that of Ce:Lu2(SiO4)O which is a well-known scintillator.In the energy levels structure of Ce:LaAlO3 and Ce:Lu2(SiO4)O,the lowest 5d energy level of Ce 3+ is located below the bottom of the conduction band of host crystal and the other higher 5d energy levels of Ce 3+ are located above the bottom of the conduction band of host crystal.The second one is:Ce:LaAlO3 single crystal may not be suitable for scintillation application;by comparing the energy levels structures of Ce:LaAlO3 and Ce:Lu2(SiO4)O,the large energy difference(1.13 eV)between the two lowest 5d energy levels of Ce 3+ in LaAlO3 is a crucial factor that causes the luminescence quenching.