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We studied a magnetic levitation system using the magnetic shielding effect of a GdBCO bulk superconductor. One set of permanent magnet, ferromagnetic rail, and HTS bulk is called the basic model. To increase the magnetic levitation force, we place two basic models side by side. There are two kinds of models. The first has the S poles of the permanent magnets in both modules on the upper side and is named the 2-set (SS) model. The second has the S pole on the upper side of the permanent magnet and the N pole on the upper side of the other permanent magnet, and is called the 2-set (SN) model. The levitation force of the 2-set (SS) and (SN) models was more than twice that of the basic model. To support the experimental approach, we numerically evaluate a magnetic flux distribution using finite element method software.

Cooling performance of Yb : glass was improved with an index-matching liquid. 1-bromonaphthalene was used in the interfacial gap of hybrid gain material between Yb : glass and sapphire blocks. Thermal lens effects under an intensity of 20 kW cm−2 were effectively reduced. The improved hybrid gain material Yb : glass and sapphire can increase repetition rates of laser systems.

A new mechanical alloying process for preparing amorphous powders by rubbing more than two types of elemental metal against each other under a certain pressure has been developed. A rotating bundle of Cu and Ti sticks pressed on the concave side of a Ti mortar is used to prepare a fine powder. The micromorphology of the powder was examined using scanning electron microscopy and optical metallography. Energy-dispersive X-ray spectroscopy analysis shows that the powder was not contaminated at all. The alloying procedure was investigated by X-ray diffraction analysis and differential scanning calorimetry. The fine powder mechanically alloyed for several hours showed the broad X-ray scattering maxima and the exothermic heat peak of thermal analysis curve referring to the amorphization and crystallization, respectively.

We report on experiments with high-power femtosecond pulses from a passively mode-locked thin disk Yb:YAG laser: nonlinear fiber compression to 33 fs with 18 W average power and a fiber-feedback parametric oscillator generating 15 W in the 1.5-/spl mu/m region.

We present a red-green-blue laser source with average powers of 8 W in the red, 23 W in the green, and 10.1 W in the blue. The entire pump power for the nonlinear conversion stages is provided by a single laser oscillator without any amplifier stages. Our system does not require any synchronized cavities, and all nonlinear crystals except one are critically phase matched at room temperature.

With a passively mode-locked thin disk Yb:YAG laser we pumped a two-stage optical parametric generator producing ultrashort pulses with 11 W average power at 799 nm and 6 W at 1448 nm. Sum frequency mixing of the latter two wavelengths with residual 1030-nm light results in multi-watt output powers at 450 nm and 602 nm.

Summary form only given. We present a parametric generator based on the novel nonlinear material periodically poled stoichiometric LiTaO/sub 3/ (PPSLT) and a recently developed high-power femtosecond Yb:KY(WO/sub 4/)/sub 2/ (Yb:KYW) thin-disk laser. We achieved simple and robust single-pass OPG at the full repetition rate of 24 MHz. We obtained stable 1 W signal power in 320 fs-pulses with a good transverse beam quality (M/sup 2/ = 1.1) at 1.45 /spl mu/m and 0.6 W of idler power at 3.55 /spl mu/m for 7.8 W pump power. For a few minutes, even 2.5 W of signal output power have been achieved. The damage resistance of PPSLT seems to be significantly better than for congruent PPLN.

The effects of absorbed water of spin-on glass (SOG) and tetraethylorthosilicate (TEOS)-O/sub 3/ NSG on MOS transistor hot carrier degradation were investigated. It was found that the absorbed water in SOG and TEOS-O/sub 3/ NSG film desorbs from the film during subsequent low temperature annealing and causes hot carrier degradation. It was also found that plasma CVD silicon oxide (P-SiO) deposited under certain conditions suppresses the hot carrier degradation drastically. Because the P-SiO film has a small water absorption rate, it blocks water penetration to the silicon surface. >

We demonstrate a synchronously pumped high-gain OPO with feedback through a fiber, using an Yb:YAG thin disk laser as pump source. We obtained 15.5 W average signal power at a wavelength of 1.45 μm in 630-fs pulses.

Laser processing on a silicon plate was observed. A free running flashlamp pumped Ti:sapphire laser was used. A pair of PIN detectors was useful for the detection of penetration. The photographs of keyhole were taken by laser microscopy.

Publisher Summary This chapter deals with an elastoplastic large deformation analysis of unstiffened plates subjected to a pure shear loading. An analytical model, on which all edges are simply supported for out-of-plane displacements, but kept straight for in-plane displacements, is developed. In this model, the lower edge is constrained and an in-plane horizontal displacement is specified on all nodes of the upper edge in order to introduce a shear deformation. Rotations about y- and z-axes on these two edges are restrained. Two unloaded edges are constrained to model the infinitely rigid bar by introducing a Multipoint constraint (MPC) boundary condition. The distribution of residual stresses assumed is a pattern, typical of an edge-welded plate, i.e., an ideal rectangular pattern, as might conceivably be induced by welding along the simply supported unloaded edge. The ductility of unstiffened plates is influenced by the width-thickness ratio and an approximated equation that is a lower bound curve covering. The effect of loading history was proposed to determine failure strains of unstiffened plates used as web plates in flame structures constructed in seismic areas.

We analyze the physical processes in the nonlinear wavelength conversion stages of a recently demonstrated red-green-blue (RGB) laser source, which generated > or = 8 W of average power in each color. The system is based on an infrared femtosecond mode-locked laser and contains a frequency doubler, a parametric generator, a parametric amplifier, and two sum-frequency conversion stages. It does not require any resonant cavities, external laser amplifiers, or nonlinear crystals operated at elevated temperatures; therefore it appears to be more practical than other previously demonstrated RGB laser sources. However, the optimization of the overall system is nontrivial, because pump depletion, birefringence, and temporal walk-off in the first conversion stages lead to spatial and temporal distortion of the interacting beams in the subsequent nonlinear conversion stages. This leads to the interaction of spatially and temporally distorted beams in the later conversion stages. By using a numerical simulation of the nonlinear conversion processes based on a Fourier-space method in one temporal and two transverse spatial dimensions, we can fully take into account these effects. We analyze and discuss the physical effects in the different conversion stages and describe the optimization of the overall system performance.

We report a noncollinear optical parametric generator (OPG) using periodically poled LiNbO 3 (PPLN) pumped by a Nd:YAG laser. Signal tuning is achieved from 1.58 to 1.81 μm by angular rotation of the PPLN crystal. A signal linewidth of 68 nm was found at 1.76 μm. A 532-nm-pumped narrow-linewidth OPG is employed for its idler to serve as a seed source for the Nd:YAG-pumped broadband OPG. Tuning the seed wavelength only, tuning of the noncollinear OPG is achieved, with its linewidth reduced to 1.7 nm throughout its bandwidth. Such a system can be employed for wavelength division multiplexing, optical coherence tomography, and spectroscopy.

We present a simple scheme to generate a continuously tunable pulsed narrow-bandwidth infrared wave. An Nd:YAG-pumped periodically poled lithium niobate optical parametric generator (OPG) is seeded with the output of another OPG pumped by the second harmonic (0.532 microm) of the Nd:YAG laser. A tunable idler wave from the 0.532-microm pumped OPG, operated away from the degenerate point, provides a narrow linewidth seed source for the 1.064-microm pumped broadband OPG. Seeding forces the second OPG to operate in a narrowband operation comparable with that of the seed source. Linewidth of the YAG-pumped OPG is 5-25 nm, in the tuning range of 1.61-1.83 microm (signal), narrowed to 1.48-1.05 nm. Methods of further reduction of linewidth also have been discussed.

Effects of Si surface orientation on small dimension NMOS and PMOS characteristics at 300K and 77K have been experimentally investigated. Carrier transport in a high electric field and hot carrier-induced degradation have been examined in detail. In scaled NMOS devices alone, a triode channel transconductance depends strongly on Si surface orientation, but a pentode transconductance does not depend on it. These behaviors are qualitatively discussed with an effective mass model and carrier transport process. The Si surface orientation dependence of hot carrier-induced degradation is found to be related to the number of interface state. Based upon these results, the optimum surface orientation for submicron CMOS devices is discussed.

Oxygen concentration in as-grown silicon crystals was controlled by doping oxygen intentionally. Oxygen concentration depended linearly on the surface area of fused quartz pieces placed at the bottom of Si3N4 crucible which is made by CVD using SiCl4+NH3→Si3N4 reaction.

The effect of welding on the local buckling of aluminium thin-walled sections is focused in this paper. With regard to a round-house type law material and by considering different hardening parameters as well as plate slenderness, the effect of welding in terms of geometrical imperfections, residual stresses and heat affected zones are analysed by means of a finite element analysis. The obtained results emphasise the influence of welding on the strength of slender plates, which has been only partially evidenced by experimental analyses. Besides, the comparison with the new EC9 approach allows to check the reliability of the design curves with respect to such a phenomenon.