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Under Lagrange coordinates, the relativistic spherical plasma wave in a collisional and warm plasma is discussed theoretically. Within the Lagrange coordinates and using the Maxwell and hydrodynamics equations, a wave equation describing the relativistic spherical wave is derived. The damped oscillating spherical wave solution is obtained analytically using the perturbation theory. Because of the coupled effects of spherical geometry, thermal pressure, and collision effect, the electron damps the periodic oscillation. The oscillation frequency and the damping rate of the wave are related to not only the collision and thermal pressure effect but also the space coordinate. Near the center of the sphere, the thermal pressure significantly reduces the oscillation period and the damping rate of the wave, while the collision effect can strongly influence the damping rate. Far away from the spherical center, only the collision effect can reduce the oscillation period of the wave, while the collision effect and thermal pressure have weak influence on the damping rate.

Ta2O5 films are deposited on fused silica substrates by conventional electron beam evaporation method. By annealing at different temperatures, Ta2O5 films of amorphous, hexagonal and orthorhombic phases are obtained and confirmed by x-ray diffractometer (XRD) results. X-ray photoelectron spectroscopy (XPS) analysis shows that chemical composition of all the films is stoichiometry. It is found that the amorphous Ta2 O5 film achieves the highest laser induced damage threshold (LIDT) either at 355 or 1064 nm, followed by hexagonal phase and finally orthorhombic phase. The damage morphologies at 355 and 1064 nm are different as the former shows a uniform fused area while the latter is centred on one or more defect points, which is induced by different damage mechanisms. The decrease of the LIDT at 1064 nm is attributed to the increasing structural defect, while at 355nm is due to the combination effect of the increasing structural defect and decreasing band gap energy.

CaS phosphor activated with Dy ions is prepared by the solid-state diffusion method. The phosphor is characterized by x-ray powder diffraction, thermogravimetric analysis and photoluminescence. Defect centres formed in CaS:Dy are studied using the technique of electron spin resonance. The thermoluminescence glow curve shows peaks at around 117 degrees C and 345 degrees C. Irradiated CaS:Dy exhibits ESR lines due to defect centres. The thermal annealing behaviour of one of the defect centres appears to correlate with the TL peaks at 117 degrees C and 345 degrees C. This centre is characterized by an isotropic g-value of 2.0035 and is assigned to an F+- centre.

A theory is developed for incoherently coupled grey photovoltaic soliton families in unbiased photovoltaic crystals. Both the properties and the forming conditions of these soliton families are discussed in detail. The theory can also be used to investigate the dark photovoltaic soliton families. Some relevant examples are presented, in which the photovoltaic-photorefractive crystal is of lithium niobate type.

We present a generalized soliton theory based on the one-dimensional generalized nonlinear Schrodinger equation, from which one can easily obtain the bright, dark, and grey soliton waveforms, and their existence curves. We show that the forming conditions of spatial solitons are directly dependent on the relationship between the index perturbation and the intensity, no matter whether the index perturbation is positive or negative. Some relevant examples are presented when the solitons are supported by the photoisomerization nonlinearity.

The properties of the spontaneous emission from a three-level atom with an external driving field in a photonic crystal are studied. The population in the two upper levels displays complete decay or oscillatory behavior, depending on the initial atomic state and the relative position of the two upper levels from the forbidden gap. The intensity and the phase of the external field can also affect spontaneous emission from the atom.

We investigate the optical response of a metallic wire calculated from the classical electromagnetic theory. The Drude (local) approach is compared with the semi-classical hydrodynamical theory calculations that reveal the Fano-like resonances of subsidiary peaks originated from the nonlocality. The bulk plasma resonances containing the nonlocal effects could be depressed by increasing the dissipation, while the blue shift of the surface localized plasma resonances could be enhanced by increasing the Fermi velocity.

The interaction between particles cannot be ignored when a high frequency electromagnetic wave is incident on a mixed media. Strong fluctuation theory with correlation function is a suitable method to describe the problem. Materials with honeycomb sandwich structures with an absorber included are investigated. The effective electromagnetic parameters and reflection coefficient of these materials are deduced and numerical results are given. Compared with the method with a disturbing term not considered, this method shows better absorbing properties.

The electron transport properties of a silicon atomic chain sandwiched between Au (100) leads are investigated by using the density functional theory combined with the non-equilibrium Green's function method. The breaking process of Au-Si4-Au nanoscale junctions is simulated. The conductance and the corresponding cohesion energy as a function of distance dz are obtained. With the increase of distance, the conductance decreases. When dz = 18.098 A, there is a minimum value of cohesion energy. The nanoscale structure of junctions is most stable, and the equilibrium conductance is 1.71G0 (G0 = 2e2/h) at this time. The I—V curves of junctions at equilibrium position show linear characteristics.

The terahertz radiations generated through a slab of GaAs-based photoconductive antennas are calculated from the nonlinear model and measured by a time domain spectroscopy system. The calculated spectra for the different pulses are in agreement with our experimental observations. This consistency suggests that the description of the nonlinear model captures the basic features of this photoelectrical terahertz emission mechanism. Furthermore, 1/f background noise dominates the terahertz detection in our experiments when the frequency is larger than 3 THz.

A hybrid high-frequency method is proposed to analyze the bistatic electromagnetic scattering of the ship target on a very large two-dimensional randomly rough sea surface. The scattering of the ship-sea model is evaluated with the method of equivalent currents (MEC). The iterative physical optics method (IPO) is utilized to study the electromagnetic coupling effect caused by the hull and rough surface. The shadowing correction based on the Z-Buffer technology is introduced to eliminate the effects of the irrelevant scattering resources. The validity of the hybrid method is confirmed by the SAR simulation results and the scattering property of the ship-sea model is discussed.

Chirped mirrors (CMs) are designed and manufactured. The optimized CM provides a group delay dispersion (GDD) of around –60 fs2 and average reflectivity of 99.4% with bandwidth 200 nm at a central wavelength of 800 nm. The CM structure consists of 52 layers of alternating high refractive index Ta2O5 and low refractive index SiO2. Measurement results show that the control of CM manufacturing accuracy can meet our requirement through time control with ion beam sputtering. Because the GDD of CMs is highly sensitive to small discrepancies between the layer thickness of calculated design and those of the manufactured mirror, we analyze the error sources which result in thickness errors and refractive index inhomogeneities in film manufacture.

On the basis of band calculation results and a universal superconducting mechanism for oxide systems proposed previously by the authors, the superconducting transition temperatures are calculated for Ba(Pb1-xBix)O3 with x=0 and 0.1, which are in good agreement with experimental results. The composition and pressure dependences of Tc and normal state resistivity in various oxide systems can be interpreted.

The highest superconducting transition temperature of 8.42 and 5.16K has been observed in the alloy system PdH and PdCuH, where the atomic ratio n=H/Pd(Cu) are 1 and 0.6, respectively. The effect of lattice disorder induced by 220 keV Ar ion beam bombardment at liquid helium-temperature is detrimental to the superconductivity.

The resistivity, Meissner effect and specific heat measurements were carried out on high Tc superconductor Ba2GdCu3 O7-y with zero-resistivity at 95.5K. It was found that the deviation of resistivity from linear behavior below 125K seemed not to originate from precursory signal of superconductivity but from possible lattice softening that may play an important role in 90K superconductivity.