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We perform first-principles density-functional theory calculations to study the atomic and electronic properties of early transition metals (Zr, Ti, Y, and Sc) codoped with N in wurtzite ZnO. By incorporating early transition metals Ti, Zr, Y, and Sc with N into ZnO simultaneously, we find that forming complexes (Zr-2N), (Ti-2N), (Y-N), and (Sc-N) induces fully occupied impurity bands with the N 2p character above the valence band maximum of host ZnO. With further doping of N in ZnO, the systems (Zr-2N):N, (Ti-2N):N, (Y-N):N, or (Sc-N):N have acceptor ionization energies lower than that of the isolated N acceptor in ZnO. Under different growth conditions (i.e., using an N2O or NO source for the nitrogen atoms), we calculate the formation energies of the defect complexes and compare the dopability of the selected codoped systems. Our results show that the valence band maximum characteristic of ZnO can be altered by compensated donor-acceptor pairs, thus improving the p-type dopability. [ABSTRACT FROM AUTHOR]

A stable output, high power diode-pumped Tm: YLF laser operating at 1908 nm with FWHM line width less than 0.1 nm is reported. Using a volume Bragg grating, 41.1 W of output with M2∼2 under an incident pump power of 111.7 W was achieved, corresponding to an optical-to-optical conversion efficiency of 36.8% and a slope efficiency of 43.2%. A laser wavelength shift of only 0.3 nm with the incident pump power varying from 13.1 W to 111.7 W was observed. [ABSTRACT FROM AUTHOR]

We report continuous-wave (CW) and repetitively Q-switched operation of an in-band-pumped Ho:LuAG laser at room temperature. End-pumped by a Tm:YLF solid-state laser with emission wavelength of 1.91 μm, the CW Ho:LuAG laser generated 5.4-W output at 2100.7 nm with beam quality factor of M2∼1.03 for an incident pump power of 14.1 W, corresponding to slope efficiency of 67% with respect to absorbed pump power. Up to 1.5-mJ energy per pulse at pulse repetition frequency (PRF) of 3 kHz and 4.5-W average power with FWHM pulse width of 28 ns at 5 kHz were demonstrated in repetitively Q-switched operation. [ABSTRACT FROM AUTHOR]

We report the continuous wave and acousto-optically Q-switched operation of a Tm:YLF-pumped Ho:YAP laser at room temperature. Continuous wave output power of 6.8 W at 2118 nm was obtained under the incident pump power of 13.4 W, corresponding to a slope efficiency of 65.6% and a conversion efficiency of 50.7%. For the Q-switched mode, a maximum pulse energy of 1.28 mJ and a minimum pulse width of 31 ns at the repetition rate of 5 kHz were achieved, resulting in a peak power of 41.3 kW. In addition, the Ho:YAP laser was employed as a pumping source of ZGP optical parametric oscillator, the total average output power of which was 3.2 W at 4.08 and 4.41 μm with a slope efficiency of 69.5%, corresponding to the diode-to-mid-IR conversion efficiency of 9.0%. [ABSTRACT FROM AUTHOR]

We demonstrate anti-misalignment acousto-optically (AO) Q-switched Ho: YLF ring cavity laser with a single corner cube prism (CCP) as the cavity mirror and a diode-pumped 1940 nm solid state laser as the pump source. We study the polarization state of oscillating light of ring cavity with the CCP by simulation calculations, which matched with the experimental results. In the continuous wave (CW) operation, the Ho: YLF laser achieves a total bidirectional output power of 3.8 W at the wavelength of 2063.5 nm, corresponding to an optical-to-optical conversion efficiency of 15% and a slope efficiency of 50.7%. The maximum allowable deviations of the CCP are 0.57° (pitch angle) and 1.65° (horizontal angle), respectively. We obtain a single pulse energy of 17 mJ and a pulse width of 113 ns at a pulse repetition frequency (PRF) of 100 Hz. The beam quality factors in the horizontal and vertical directions are M x 2 = 1.01 and M y 2 = 1.06, respectively, which are approached to the diffraction limit. [ABSTRACT FROM AUTHOR]

The interaction of advanced glycation end products (AGE) and their specific cell-surface receptor (RAGE) has an important role in the pathogenesis of cardiovascular disease and diabetic complications. Two isoforms of C-truncated RAGE, soluble RAGE (sRAGE) and endogenous secretory RAGE (esRAGE), may prevent activation of RAGE signaling by acting as decoys. This study investigated whether serum esRAGE and sRAGE levels are associated with blood pressure in nondiabetic patients with obstructive sleep apnea (OSA). Male nondiabetic patients (n=139) with OSA were enrolled. Serum esRAGE and sRAGE levels were examined using enzyme-linked immunosorbent assay. Three consecutive seated systolic blood pressure (SBP) and diastolic blood pressure (DBP) measurements were obtained at 5-min intervals in the morning. In univariate analysis, there was a significant correlation between serum esRAGE and SBP or DBP, but not between serum sRAGE and SBP or DBP. Multiple regression analysis showed that SBP was independently associated with waist circumference, HbA1c, minimum SaO2 and serum esRAGE, and that DBP was independently associated with low-density lipoprotein cholesterol, apnea-hypopnea index, serum AGE and body mass index, but not with serum esRAGE. These results indicated that serum esRAGE levels were inversely associated with blood pressure, especially SBP, in male nondiabetic patients with OSA. esRAGE may have a protective role against hypertension in patients with OSA, and it may be a novel biomarker for OSA patients at high risk of developing cardiovascular diseases. [ABSTRACT FROM AUTHOR]

A log-pile photonic crystal of CdS nanoparticles–polymer nanocomposites was successfully fabricated by a novel method combining the two-photon polymerization technique and in situ synthesis of CdS nanoparticles in a polymer matrix. The photonic band gap of the three-dimensional (3D) log-pile photonic crystal is confirmed and becomes more effective for CdS nanoparticles–polymer nanocomposites than polymer doped with Cd2+ ions, because the nanocomposites possess a higher refractive index than the polymer. The proposed concept in the new fabrication method for a 3D microstructure of polymer nanocomposites should be of critical importance in providing a general methodology for functionalization of materials via functional nanocomposites used in the field of laser microstructure fabrication. [ABSTRACT FROM AUTHOR]

A photodetector pixel using a photonic crystal structure incorporating photoconductive layers has been realized. The fabricated device exploits mode discrimination and resonant cavity enhancement to provide simultaneous multispectral detection capability, high quantum efficiency, and dramatically suppressed shot noise. Detectivities as high as 2.6×1010 and 2.0×1010 cm Hz1/2 W-1 at the two preselected wavelengths, 632 and 728 nm, were achieved, respectively. [ABSTRACT FROM AUTHOR]