A comparative study on diode-pumped continuous wave Tm:Ho:YVO<Subscript>4</Subscript> and Tm:Ho:GdVO<Subscript>4</Subscript> lasers

In this paper, we presented experimental results concerning on the laser characteristics of two microchip lasers emitting in the 2 μm range, Tm:Ho:YVO₄ microchip laser and Tm:Ho:GdVO₄ microchip laser. At a heat sink temperature of 283 K, the maximum output power of Tm:Ho:YVO₄ laser and Tm:Ho:GdVO₄ laser is 47 and 34 mW under absorbed pump power of 912 mW, respectively. High efficiency can be achieved for both lasers at room temperature. Nevertheless, compared with Tm:Ho:GdVO₄ laser, Tm:Ho:YVO₄ laser can operate on single frequency with high power easily. At the heat sink temperature of 288 K, as much as 16.5 mW of 2052.3 nm single-longitudinal-mode (SLM) laser was achieved for Tm:Ho:YVO₄ laser. Under the same condition, only 8 mW of 2048.5 nm SLM laser was achieved for Tm:Ho:GdVO₄ laser.     

Diode-end-pumped Tm,Ho:YVO<Subscript>4</Subscript> microchip laser at room temperature

Room temperature Tm, Ho:YVO₄ microchip laser operated around 2 μm was demonstrated for the first time to our knowledge. At a heat sink temperature of 283 K, a maximum output power of 47 mW was obtained by using a 0.25 mm length crystal at an absorbed pump power of 912 mW, corresponding to a slope efficiency of 9.1%. Increasing the temperature to 288 K, as much as 16.5 mW 2052.3 nm single-longitudinal-mode laser was achieved. The M ² factor was measured to be 1.4.     

Extraction of Cu<Superscript>2+</Superscript> from aqueous solutions using microcapsules containing ionic liquid [BMIM]PF<Subscript>6</Subscript>

Polysulfone (PSF) microcapsules filled with ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF₆] were successfully prepared via solvent evaporation method. The encapsulation capacity of 38.0% was achieved. Microcapsules showed a spherical, porous honeycomb structure. The size of microcapsules was approximately 110 μm and the thickness was approximately 10 μm. Microcapsules have excellent thermal stability, with a higher thermal degradation onset temperature of 360°C compared to traditional extractant-loaded microcapsules. Microcapsules were used to extract Cu²⁺ from aqueous solutions. The effect of chelator, pH, PSF, and ionic liquid on the extraction rate were studied. When chelator was added in aqueous solutions, and the pH of aqueous solutions was 4.5, the extraction rate of microcapsules reached the maximum value, which was 99.0%. These PSF microcapsules containing [BMIM][PF₆] showed potential ability in the treatment of wastewater.     

Synthesis,crystal structure,and fluorescence properties of a two-dimensional copper(II) complex with Schiff base

A new Schiff base ligand C₁₉H₁₃NO₅(H₂L) was synthesized using 2-aminoterephthalic acid and 2-hydroxy-1-naphthaldehyde. A complex of this ligand [Cu(C₁₉H₁₁NO₅)(C₂H₆O)] _n was synthesized and characterized by IR, UV, fluorescence spectroscopy and X-ray diffraction single-crystal analysis. The crystal crystallizes in the monoclinic system, space group Pbca with a = 8.7745(18), b = 18.613(4), c = 24.644(5) Å, V = 4024.9(14) ų, Z = 8, F(000) = 1816, S = 1.009, ρ _calcd = 1.462 g cm^?3, μ = 1.122 mm^?1, the final R = 0.0477 and wR = 0.1594 for 4609 observed reflections (I > 2σ(I)). The Cu(II) is five-coordinated by one N atom and two O atoms from the Schiff base ligand and two carboxylate O atoms from another two ligands to form a distorted square-pyramidal geometry. Each ligand serves as a bridging ligand to link Cu²⁺ ions, leading to a two-dimensional coordination polymer. The fluorescence properties of the ligand and complex were also studied. The ligand shows strong fluorescence, and the fluorescence intensity is weakened after the Cu(II) complex formed.     

Component effects on the vanadium oxide thin films phase transition character phenomenon observed

We present what is, to the best of our knowledge, how the components affect the phase transition character of the vanadium oxide thin films. The vanadium oxide thin films are prepared on zinc selenide by a DC magnet sputtering method for the first time; the components are achieved by the x-ray photoelectron spectroscopy (XPS). The films are annealed to tune their components. A spectral transmittance study has been made from 2.5 to 25.0 μm. We can see that, except for doping, different components can change the phase transition characters of the films. The components can affect the phase transition temperature, hysteresis cycle, and the transmittance.     

The inflation class operator

We consider the inflation class operator, denoted by F, where for any class K of algebras, F(K) is the class of all inflations of algebras in K. We study the interaction of this operator with the usual algebraic operators H, S andP, and describe the partially-ordered monoid generated by H, S, P andF (with the isomorphism operator I as an identity). Received February 3, 2004; accepted in final form January 3, 2006.     

Transmission property for a one-dimensional photonic crystal containing a subwavelength layer and a nonlinear layer

Using the transfer matrix method, we investigate the transmission property of a one-dimensional photonic crystal doped with a linear subwavelength layer and a Kerr-type nonlinear layer. We find that a thin film of subwavelength layer can significantly modify the characteristic of optical bistability. We also find that the sequence of the thin film and the nonlinear layer has a major impact on the hysteretic behavior. With the investigations to the linear defect mode and the electric field distribution in the nonlinear material, we explain these phenomena. PACS 42.65.Pc; 42.25.Bs; 42.70.Qs; 42.65.-k; 78.66.-w     

“Positive” and “negative” electric-pulse-induced reversible resistance switching effect in Pr<Subscript>0.7</Subscript>Ca<Subscript>0.3</Subscript>MnO<Subscript>3</Subscript> films

“Negative” electric-pulse-induced reversible resistance (EPIR) switching phenomenon was found in In/PCMO/Pt sandwich, in which the high resistance can be written with positive voltage pulses, and the low resistance can be reset using negative voltage pulses (the positive voltage direction is defined as going from the top electrode to the bottom electrode). This is just the opposite from the “positive” EPIR effect in Ag/PCMO/Pt sandwich, in which the high resistance can be written only with negative voltage pulses, and the low resistance can be reset using positive voltage pulses. The I–V hysteresis curves of In/PCMO/Pt and Ag/PCMO/Pt sandwiches also show opposite directions, i.e., counterclockwise and clockwise under a negative voltage region for indium and Ag electrode systems, respectively. C–V characteristics show that the barrier does not exist in Ag/PCMO/Pt sandwich, while In/PCMO/Pt sandwich exhibits an obvious Schottky-like barrier. We suggest that in the negative EPIR behavior in In/PCMO/Pt structure, the resistance states are mainly controlled changing the Schottky-like barrier at the interface with the weak effect of carrier trapping process, while the positive EPIR behavior in Ag/PCMO/Pt sandwich mainly depends on the carrier trapping process at the interface. PACS 72.80.-r; 73.40.-C; 75.70.-i     

Compact TEM<Subscript>00</Subscript> grazing-incidence Nd:GdVO<Subscript>4</Subscript> laser using a folded cavity

A compact diode-side-pumped Nd:GdVO₄ laser system using a folded cavity and grazing-incidence configuration is presented. The highest multimode output power obtained was 21.8 W at 36 W of effective diode pump power. Highest optical-to-optical conversion efficiency of 61.5% was achieved at 33 W of effective diode pump power with 20.3 W of multimode output power. For single-mode TEM₀₀ operation, an intracavity telescope was adopted for mode matching in the horizontal direction. Because of the folded cavity and the intracavity telescope, this laser head was the most compact to our knowledge of the TEM₀₀ grazing-incidence laser geometry. At last, an output power of 15 W was produced at 36 W of effective diode pump power. The stable Q-switching operation was also obtained. PACS 42.55.-f; 42.55.Xi; 42.60.Gd     

Hydrogen-enhanced recrystallization in N<Superscript>+</Superscript>-implanted GaAs

The hydrogen-enhanced recrystallization during thermal annealing in N⁺-implanted GaAs has been studied by combinatorial implantation process. Raman spectroscopy was used to study the crystallization properties of a set of hydrogenated cells on the N⁺-implanted GaAs wafer. A whole competitive process between H⁺ implantation-induced damage and recovery in the regrowth process of amorphous GaAs was observed within the proton dose region of 1.6×10¹⁵ to 1.1×10¹⁷ cm^-2. In H⁺ dose region of 2.1×10¹⁶ to 5.4×10¹⁶ cm^-2, H-enhanced recovery of crystal dominates the regrowth process. The crystal quality is better than that of unhydrogenated cell of N⁺-implanted GaAs in the H⁺ dose range from 4.7×10¹⁶ to 8.1×10¹⁶ cm^-2. It is suggested that the vacancy supersaturation produced during hydrogen irradiation is dominantly responsible for the enhancement of thermal regrowth in the N⁺-implanted GaAs. Both the crystallization and amorphization process are clearly observed in different proton implantation dose regions. PACS 61.72.Vv; 63.20.Dj; 81.05.Ea