Shunguang Li

Optical and thermal properties of a new Nd-doped phosphate laser glass

In this paper, we report the optical and thermal properties of a new Nd-doped phosphate laser glass. Glass samples with 0.5-3.7 wt% Nd-doping concentrations were prepared, annealed, cut and polished for different measurements, including glass density and refractive index, absorption spectra and emission cross section, as well as laser properties. A Mach- Zehnder interferometer was used to measure the temperature coefficient of refractive index (dn/dT) and optical path length (dS/dT) in the temperature range of 30-100 °C. Moreover, by increasing the glass temperature up to 500 °C, the thermal expansion of this new glass was also measured. On the basis of these optical, thermal and thermo-optic parameters, we calculated and analyzed some of glass parameters, such as the electronic polarizability of oxygen ions, the optical basicity of this phosphate-based glass, and especially discussed their thermal shock resistance properties. It is suggested that this new Nd-doped phosphate laser glass is an excellent candidate for high energy and high repetition rate laser applications.

Thermal loading in laser diode end-pumped Yb3+/Er3+ codoped phosphate glass laser

We investigate, based on laser performance, the fractional thermal loadings in a Yb(3+)/Er(3+) codoped phosphate glass laser. The results indicate that fractional thermal loading increases with Er(3+) doping concentration nonlinearly. Above an Yb(3+) doping level, the increase of Yb(3+) cannot promote laser performance but induces a more serious heat effect. We investigate the main factors that simultaneously affect laser and thermal performances. The results show that the ratio of laser output power to heat is sensitive to beam overlap efficiency, the laser extraction efficiency, especially to quantum efficiency of laser material. The optimized doping concentrations of Yb(3+) and Er(3+) are deduced.

Spectroscopic properties of Yb3+-doped PbWO4 single crystal

Abstract Yb 3+ -doped PbWO 4 single crystal was grown using modified vertical Bridgman method. X-ray diffraction (XRD) analysis, optical absorption spectra, X-ray excited luminescence (XEL), fluorescence of 2 F 5/2 → 2 F 7/2 and its lifetime at room temperature were investigated. PWO:Yb 3+ shows the broad absorption of Yb 3+ (850–1050 nm) and efficient emission (950–1100 nm). Annealing exerts a distinct influence on the PWO:Yb 3+ crystal, e.g. disappearance of color and annihilation of the absorption in the region around 450–750 nm, meanwhile the absorption of Yb 3+ ions was enhanced by the annealing treatment. A novel luminescence band on the X-ray excited luminescence spectra of PWO:Yb 3+ centered at about 500 nm was observed overlapped on that of PWO host.

Determination of energy transfer and upconversion constants for Yb 3+ /Er 3+ codoped phosphate glass

The energy transfer and cooperation upconversion processes are investigated in Yb3+/Er3+ codoped phosphate glass. Based on the measured curves of output power versus incident power, the laser and spectroscopic parameters of the glass are fitted and analyzed. We focus on the resonant energy transfer constant k from Yb3+ to Er3+ as well as the cooperation upconversion coecient Cup from 4I13/2 of Er3+. The fitted k and Cup can give almost the same results for different thicknesses of glass disk with the same doping concentrations. The determination of these parameters is helpful for the development of Yb3+/Er3+codoped laser glass.

Additive manufacturing of cp-Ti, Ti-6Al-4V and Ti2448

Abstract Despite titanium being the ninth-most common element in the earths crust and the fourth-most abundant structural metal (after iron, aluminum, and magnesium), the high cost of reducing and refining the ore makes titanium an expensive material. Fortunately, it does possess an attractive set of properties, including high strength, low weight, and excellent corrosion resistance. Nonetheless, titanium is only used in applications where the high cost can be justified or at least tolerated. For example, the high specific strength makes the metal attractive to the aerospace industry while the high corrosion resistance sees it used in chemical processing equipment. In its commercially pure form, and in some titanium-based alloys, it is also biologically compatible in humans, which, combined with the corrosion resistance and high strength, make it attractive for biomedical devices.

The fractional thermal factor in LD-pumped Yb 3+ /Er 3+ codoped phosphate glass

The fractional thermal in LD-pumped Yb3+/Er3+ codped phosphate glass have been investigated base on the measurement of edge temperatures of glass. The temperatures of pump sopt at differernt pump power are calculated. The results indicate that upconversion processes have an important contribution to heat of LD pumped phosphate glass.