The Er-single-doped and Er/Ce-codoped La_3Ga_5SiO_(14) polycrystalline powders are synthesized by the solid-phase synthesis method.The room-temperature luminescence spectra of the samples are investigated.The Near-infraredregion spectroscopic properties of Er～(3+) ions in the La_3Ga_5SiO_(14) systems are analysed with Judd-Ofelt theory and rate equations.The effective deactivating effect of Ce～(3+) ions on Er～(3+) ions is confirmed.
Photoluminescence (PL) of Bi12GeO20 and Mo doped Bi12GeO20 (Mo: Bi12GeO20) crystals in visible and near-infrared (NIR) spectral regions were studied. X-ray diffraction analysis, absorption and Raman scattering spectra of these crystals were also measured. Pure Bi12GeO20 after annealing in N2 atmosphere at 450 oC and 550 °C show predominant emissions at about 745 and 1250 nm bands, while the emission peaks of Mo:Bi12GeO20 crystals untreated or after annealing in Ar at 300 °C are at around 538 and 1165 nm. The results suggest that annealing induces intrinsic luminescence of Bi in pure Bi12GeO20 at room temperature and Mo influences the luminescence centers of Bi12GeO20. The emission peaks of Bi12GeO20 and Mo: Bi12GeO20 probably owe to lower-valent Bi ions.
YU PingShengSU LiangBiTANG HuiLiGUO XinZHAO HengYuYANG QiuHongXU Jun
Nd-doped PbWO4 crystals are grown by using the modified Bridgman method.The spectroscopic properties of the crystals are investigated.The changes of the absorption band at 350 nm are discussed for samples annealed at 740℃ and 1040℃.The radiative lifetime of the 4 F 3/2 level is calculated by using the Judd-Ofelt theory according to the absorption spectrum of 0.5 at.% Nd-doped PbWO 4 crystal.The spontaneous Raman scattering properties of the crystals are analysed.
By using a reflective graphene oxide as saturable absorber,a diode-pumped passively mode-locked Yb3+:Sc2Si O5(Yb:SSO)laser has been demonstrated for the first time.Without extra negative dispersion compensation,the minimum pulse duration of 1.7 ps with a repetition rate of 94 MHz was obtained at the central wavelength of 1062.6 nm.The average output power amounts to 355 m W under the absorbed pump power of 15 W.The maximum peak power of the mode-locking laser is up to 2.2 k W,and the single pulse energy is 3.8nJ.
