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Self-assembled quantum dots capping with a GaAs/Gasb combined strain-reduced layer (CSRL) are grown by MBE. Their structural and optical properties are investigated by AFM and photoluminescence (PL). PL measurements have shown that stronger emission about 1.3 μm can be obtained by Sb irradiation and capping QDs with 3 ML GaAs/2ML GaSb CSRL at room temperature. The full width at half maximum (FWHM) of the PL spectrum is about 20.2meV (19.9meV) at room temperature (20K), indicating that the QDs have high uniform, The result of FWHM is much better than the recently reported result, which is due to the fact that lower QD growth rate and growth interruption after the QDs deposition are adopted in our experiments.

Effects of two compressibility parameters, i.e. the ratio of specific heats and the equilibrium pressure at the interface, on the Rayleigh–Taylor instability (RTI) growth rates are studied under the same initial conditions, which include the mass, pressure profile, and density profile of the two superposed fluids. The results obtained reconcile the stabilizing and destabilizing effects of compressibility reported in the literature. The influences of the ratio of specific heats on the RTI growth rates are not only stabilized but also destabilized. The effects of the equilibrium pressure at the interface on the growth rates are destabilized.

We propose a simple method for monitoring the axial tensile and compressive force in a structure by using a piezoelectric patch with the piezoelectric impedance based measurement. A simple approximate equation for estimating the tensile force in two different conditions, which can be calculated easily if the natural frequencies in two different states are measured, is explained in detail. On another front, the natural frequency can be very easily measured by a piezoelectric element by bonding it on the measuring subject structure, because its electric impedance of piezoelement is related to the structural mechanical impedance. Furthermore, an experiment for measuring a tensile force in a simple supported beam is carried out for validating the proposed method. The results show a good accuracy in estimating the tensile force variation by the natural frequency change measured from the piezoelement.

Mossbauer studies on the effect of substitution with 3% Al, Co, Mn atoms in the intermetallic compound of Hf0.8Ta0.2Fe2 are reported. The Al substitution leads to increase of the FM-AFM transition temperature and to decrease of the AFM-PM transition temperature. The Co substitution leads to disappearance of the FM state, only showing some FM impurity component, while Mn substituted compound indicates coexistence of FM and AFM states at low temperature. The phenomena imply complex itinerant electron properties in these magnetic systems.

The structural and luminescence properties of nanocrystalline ZrO2:Er3+ films are reported. Transparent nano-ZrO2 crystalline films doped with Er3+ have been prepared using a wet chemistry process. An intense room-temperature emission at 1527 nm with a full width at half-maximum of 46 nm has been observed, which is assigned to the 4I13/2 → 4I15/2 intra-4fn electric transition of Er3+. Correlations between the luminescence properties and structures of the nanocrystalline ZrO2:Er3+ films have been investigated. Infrared-to-visible upconversion occurs simultaneously upon excitation of a commercially available 980-nm laser diode and the involved mechanisms have also been explained. The results indicate that the nanocrystalline ZrO2:Er3+ films might be suggested as promising materials for achieving broadband Er3+-doped waveguide amplifiers and upconversion waveguide lasers.

We report the spectroscopic properties and thermal stability of Tm3+-doped Ga2O3–GeO2–Bi2O3–PbO(PbF2) glasses for 1.47-μm optical amplifications. Effects of PbF2 doping on the optical properties and thermal stability of Tm3+-doped gallate–germanium–bismuth–lead glass are investigated. The measured peak wavelength and full width at half-maximum of the fluorescence are 1465 nm and ~120 nm, respectively. Significant enhancement of the 1.47-μm emission and the lifetime of a 3H4 level with increasing PbF2 doping have been observed. The presence of GeO2 provides two potentials of increasing the thermal stability and shortening the ultraviolet cutoff band of host glasses.

Intense blue and red upconversion emissions have been observed in Yb3+/Tm3+ co-doped 0.05 K2O-0.1ZnO-0.1BaO-0.2PbO-0.2GeO2-0.35TeO2 glasses under the pump of 976-nm laser diode. The dependence of the intensity of the upconversion emissions on the Tm3+ concentration has been studied in order to determine the ion concentration and the involved mechanism. The blue emission centred at 476 nm decreases and the 792-nm red emission increases with the increasing Tm3+ concentration. Subsequently, the dependence of upconversion emission intensity on the excitation power is investigated. It is found that the intensity ratio between the 792-nm red and 476-nm blue emissions decreases with the increasing pump energy.

Utilizing the well-focused femtosecond laser with extreme high pulse intensity, we built a two-photon microfabrication and data storage system, which was introduced through several functional parts. Based on this homemade system, several three-dimensional microstructures were fabricated by two-photon polymerization, and three-dimensional data storage of six-layers was achieved by two-photon excitation with a photochromic material.

The new oxyfluoride silicate glasses of Er3+-doped 50SiO2-(50-x)PbO-xPbF2 were prepared. With increasing PbF2 content in the glass composition, the fluorescence full width at half maximum and lifetimes of the 4I13/2 level of Er3+ increase, while the refractive indices and densities decrease. Er3+-doped 50SiO2-50PbF2 glass showed broad fluorescence spectra of 1.55?mum with a large stimulated emission cross-section and long lifetimes of 4I13/2 level of Er3+. Compared with other glass hosts, the gain bandwidth properties of Er3+-doped 50SiO2-50PbF2 glass are close to those of tellurite and bismuth glasses, and have advantages over those of silicate, phosphate and germante glasses. The broad and flat 4I13/2?4I15/2 emission of Er3+ around 1.55??m can be used as host material for potential broadband optical amplifier in wavelength-division-multiplexing network system.

A series of GaAs1-ySby epilayers are grown on GaAs substrates under different growth conditions. Different antimony compositions of samples with beryllium doping are obtained. A non-equilibrium thermodynamics model is used to calibrate and fit the Sb composition. Activation energy of 0.37eV for the dissociation process of Sb4 molecules is obtained. Carrier mobility and concentration of samples are influenced by the Sb composition. Quasi-qualitative analysis of mobility is used to explain the relations among Sb composition, carrier mobility and concentration. High resolution x-ray diffraction (HRXRD) rocking curves and Hall effects measurements are used to determine the crystal quality, carrier mobility and concentration.

Structures of strong shock waves in dense plasmas are investigated via the steady-state Navier?Stokes equations and Poisson equation. The structures from fluid simulation agree with the ones from kinetic simulation. The effects of the transport coefficients on the structures are analysed. The enhancements of the electronic heat conduction and ionic viscosity both will broaden the width of the shock fronts, and decrease the electric fields in the fronts.

The finite-difference-time-domain method is applied to simulate the two-dimensional propagation of a p-polarization mode electromagnetic wave in atmospheric plasma and metal layer for strong electron–neutral collisions. It is indicated that for a giving electron density profile, the p-polarization attenuation is very different from the s-polarization attenuation and it depends even strongly on the incident angle. The mechanism of p-polarization attenuation is analysed by the interference of wave and the relationship between the attenuation property and the main parameters is given.

The propagation property of an electromagnetic wave in a thin plasma layer at high pressure is investigated with the finite-difference time-domain method. The effects of the non-uniformity of plasma distribution, and the frequency of incident wave on the propagation property of the electromagnetic wave are discussed. Numerical results indicate that the phase shift and the reflectivity of wave are sensitive to plasma density distribution, and reflectivity is lower at the middle band of frequency for different plasma distributions.

Novel Er3+ doped TeO2-based glasses containing PbS have been prepared in argon atmosphere in carbon crucibles. The thermal analysis and spectroscopic properties of those glasses have been considered in terms of sulfide influence. Judd–Ofelt theory is introduced to calculate the bandwidth and the emission cross-section. The results demonstrate that addition of PbS into tellurite glasses results in increasing bandwidth from 71.8 to 78.4 nm, for improving emission cross-section from 6.6 to 8.1×10−21 cm2 and slightly decreasing emission lifetime from 3.4 to 3.1 ms compared to pure oxide glass.

Novel lead-bismuthate glasses with low OH concentration have been obtained in the Bi2O3–PbO–SrO system. The role of the different components in the glass formation has been explored from the density, refractive index measurements, indicating that the physical properties are mainly affected by Bi2O3 and PbO contents. The densities and refractive indices of these glasses are in the ranges of 7.639–7.699 g/cm3 and 2.47–2.94, respectively. A wide transmitting window from visible to infrared (IR) regions and good thermal stability for some compositions of these glasses have been observed, which make them appealing candidates for different optical applications such as upconverting phosphors, new laser materials, optical waveguides and crystal-free fibre drawing.

The upconversion properties of Tm3+/Yb3+-codoped lead chloride tellurite glass under 980 nm excitation were investigated. The intense blue (476 nm) emission and weak red (649 nm) emission corresponding to the 1G4→3H6 and 1G4→3H4 transitions of Tm3+ ions, respectively, were simultaneously observed at room temperature. The dependence of upconversion intensities on excitation power and the possible upconversion mechanisms are evaluated. The intense blue upconversion luminescence of Tm3+/Yb3+-codoped lead chloride tellurite glass can be used as potential host material for the development of blue upconversion optical devices.

We present the characterization of amplified spontaneous emission (ASE) from newly fabricated Er3+-doped tellurite fibres. When pumped at 980 nm, a very broad erbium ASE in the range 1450–1650 nm is observed. The changes of ASE with regard to fibre lengths and pumping power were measured. The output of 2 mW from an Er3+-doped tellurite fibre ASE source is obtained with the pump power of 540 mW.

New multi-component Yb:zinc–tungsten–tellurite glasses (70TeO2-(20-x) ZnO-xWO3-5La2O3-2.5 K2O-2.5 Na2O-1.0 Yb2O3 (x = 0, 15 mol%) have been presented. Thermal stability and spectroscopic properties of Yb3+ ions have been measured. The results show that TZW2 glass (x = 15 mol%) has thermal stability (Tx−Tg>160 degrees C with Tx being the onset crystallization temperature and Tg the glass transition temperature) better than TZN glass and that the stimulated emission cross-section of 1.32 pm2 for the 2F5/2→2F7/2 transition is higher than other laser glasses (QX, ADY, LY and FP), with the measured fluorescence lifetime of 0.93 ms and the broad fluorescence effective linewidth of 74.5 nm. Evaluated from the good potential laser parameters, TZW2 glass with both the minimum pump intensity (0.92 kW/cm2) and gain parameter (1.23 pm2ms) is promising for miniature solid fibre lasers or high-peak power lasers, as well as tunable lasers.

Strong upconversion luminescence of Er3+/Yb3+-doped lead halide tellurite glass under 976 nm excitation is demonstrated. Three emission bands centred at 525 nm, 545 nm, and 655 nm resulting from the transitions from the excited states 2H11/2, 4S3/2, and 4F9/2 to the ground state 4I15/2, respectively, are observed even at 60 mW pumping power. The power dependent intensity and the upconversion mechanisms responsible for the luminescence are evaluated and discussed. The obtained results might provide useful information for the developments of upconversion lasers.

The upconversion fluorescence emission of Er3+ -doped 60GeO2-20PbO-20PbF2 glass was experimentally investigated under the pump of 976-nm laser diode. The results reveal the existence of intense emission bands centred around 524, 545, and 657 nm at room temperature. The green emission at 524 and 545 nm is due to the 4S3/2 + 2H11/2→4I15/2 transition and the red emission of 657 nm originates from the 4F9/2→4I15/2 transition of Er3+. The quadratic dependence of the green and red emissions on excitation power indicates that a two-photon absorption process occurs under the 976-nm excitation. The excited- state absorption from 4I11/2 and the cross relaxation between two Er3+ ions in the 4I11/2 state contribute to the green emission. The red emission at 657 nm is attributed to the excited-state absorption and cross relaxation processes in the 4I13/2 level as well as the 4S3/2 level nonradiative transition of Er3+.

Atmospheric pressure glow discharge was observed in a surface discharge generator. The frequency of ac power supply is more than 9 kHz and the sinusoidal peak-to-peak applied voltage is 9 kV. The electric field intensity in a kind of surface discharge generators is calculated with the boundary element method. Then a two-dimensional fluid model was used to simulate the ion trapping and electron trapping in a surface discharge just before the breakdown. The simulation results are in good agreement with our observation.

A novel co-doping method of multi-rare-earth (RE) ions was demonstrated in tellurite glasses for fibre amplifiers. Fluorescence emissions at both 1.53 and 1.63 µm communication windows were firstly observed from Er3+/Yb3+/Tm3+-codoped tellurite glasses under a single wavelength pumping at 980 nm. The full width at half maximum of fluorescence at 1.53 and 1.63 µm are 55 nm and 50 nm, respectively. This codoping method of three RE ions could be applied to other low photon energy glasses, which would be possibly used for potential dual wavelength fibre-optic amplifiers to broaden the communication windows.

The effects of the ambient pressure Pambient on the bubble characteristics of pulsed discharge in water are investigated. The simulation results show that, when Pambient increases from 1 atm to 100 atm, the bubble radius R decreases from 4 cm to 7 mm, and its pulsation period decreases from 8 ms to 0.2 ms. The results also show that the peak pressure of the first shock wave is independent of Pambient, but the peak pressure of the second shock wave caused by the bubble re-expansion decreases when Pambient increases. On the other hand, the larger the ambient pressure, the larger the peak pressure of the plasma in the bubble, while the plasma temperature is independent of Pambient.

The properties of electromagnetic waves in atmospheric pressure plasmas are investigated with the Lorentz model. The effects of the electromagnetic wave frequency, plasma density, and the electron-neutral collision frequency on the attenuation of electromagnetic waves are discussed. The numerical results indicate that the wave attenuation is stronger at the region of the longer wavelength and at the higher plasma density.

The effect of air gap on the uniformity of large-scale surface-wave plasma (SWP) in a rectangular chamber device is studied by using three-dimensional numerical analyses based on the finite difference time-domain (FDTD) approximation to Maxwell's equations and plasma fluid model. The spatial distributions of surface wave excited by slot-antenna array and the plasma parameters such as electron density and temperature are presented. For different air gap thicknesses, the results show that the existence of air gap would severely weaken the excitations of the surface wave and thereby the SWP. Thus the air gap should be eliminated completely in the design of the SWP source, which is opposite to the former research results.

Highly Er3+/Yb3+-codoped single-mode phosphate glass fibre is fabricated by the rod-in-tube technique. The performances of high-concentration Er3+/Yb3+-codoped phosphate glass fibre amplifiers are investigated and discussed. An efficient optical fibre amplifier with a gain of 12.6 dB based on a 3.0 cm long Er3+/Yb3+-codoped phosphate glass fibre is demonstrated under a dual-pump configuration with two 976 nm fibre-pigtail laser diodes, which make it attractive for compact Er3+ -doped fibre amplifiers. The obtained noise figures of signal wavelength from 1525 to 1565 nm are less than 6.0 dB. Gain saturation behaviour at 1535 nm is also investigated, and the obtained saturation output power is larger than 10 dBm.

We experimentally investigate the laser characteristics of a series of short pieces of newly-developed Er3+/Yb3+ codoped single mode phosphate glass fibres via the cladding pump of a 976nm multimode laser diode. A stable continuous-wave single transverse mode laser with over 85mW at 1553 nm is generated from a 5.5-cm-long active fibre. Single mode laser output power per unit length is up to 15mW/cm. Moreover, the slope efciency is 11.8% when the pump power is below 940mW and the 3dB linewidth is 0.06nm at the maximum pump power. The numerical simulation results show that the laser emission slope efficiency can exceed 20% by means of increasing the coupling efficiency of the pump to the fibre core further.