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A novel mid-infrared (Er 0.3 Lu 0.1 Y 0.6) 3 Ga 5 O 12 laser crystal is successfully grown by the Czochralski method, the crystal structure, segregation coefficient, thermal performance, spectroscopy and 2.8 μm laser performance are studied systematically. The crystal possesses a pure garnet phase with a thermal conductivity of 4.54 W m−1 K−1. It exhibits a broader absorption band around 966 nm and some strong emission peaks at 2.6–3 μm, corresponding to the absorption cross-section of 1.39 × 10−21 cm2 at 966 nm and emission cross-section of 1.25 × 10−20 cm2 at 2822 nm, respectively. The level lifetimes of 4I 11/2 and 4I 13/2 are fitted to be 0.885 and 3.203 ms. A LD end-pumped Er:LuYGG laser has been demonstrated, achieving a maximum output power of 339 mW and a slope efficiency of 17.77 %. The primary laser wavelength is centered at 2824.76 nm. All the results indicate that the Er:LuYGG crystal is a novel and promising crystal material to realize the 3 μm laser. • A novel Er:LuYGG crystal is successfully grown by the Cz method. • Growth, thermal, spectroscopy and laser performance of Er:LuYGG crystals were studied. • A LD end-pumped Er:LuYGG laser is demonstrated with maximum output power of 339 mW. • The Er:LuYGG crystal is a potential and promising candidate to realize the 3 μm laser. [ABSTRACT FROM AUTHOR]

Ce3+ and Dy3+ co-doped Y 3 Al 5 O 12 (abbr. as Ce, Dy: YAG) single crystal was grown by the Czochralski method. As compared with the absorption spectrum of Dy: YAG crystal, the synchronous doping of Ce3+ ions into Dy: YAG crystal resulted in a wide excitation band in the 425–500 nm region peaking around 447 nm owing to the 4f→5d transition of Ce3+ ions, and inhomogeneous broadening absorption with the full width at half maximum (FWHM) from 4 nm to 39 nm. Furthermore, due to the efficient energy transfer from Ce3+ to Dy3+ ions in YAG crystal, under 447 nm excitation Ce, Dy: YAG crystal showed intense and wide characteristic yellow green emission, whose intensity increased by 12.3 times and FWHM from 12 nm to 113 nm as compared with Dy: YAG crystal. The fluorescence lifetime of Dy3+: 4F 9/2 level has increased from 693.1 μs to 2.062 ms. Based on the above results, Ce, Dy: YAG crystal would be an excellent candidate for the realization of yellow green waveband laser output. • Ce3+ and Dy3+ co-doped Y 3 Al 5 O 12 (abbr. as Ce, Dy: YAG) single crystal was grown for the first time. • Ce, Dy: YAG crystal showed enhanced and widen yellow green light emission as compared with Dy: YAG crystal. • Ce, Dy: YAG crystal would be an excellent candidate for the realization of yellow green waveband laser output. [ABSTRACT FROM AUTHOR]

Langasite crystals with an ordered structure of space group P321 are well known for their excellent piezoelectric and nonlinear optics performance. In this paper, a novel Nd3+: Ca 3 TaGa 2.1 Al 0.9 Si 2 O 14 (Nd: CTGAS) crystal with an ordered structure of space group P321 was successfully grown using the Czochralski method, which could be used as self-laser photoelastic modulators. The thermal behaviour, polarized spectroscopy, and fluorescence lifetime were characterized in detail, and excellent spectroscopic and laser properties were presented. The full width at half of the maximum (FWHM) of the 0.8 μm absorption band was 23.5 nm for σ-polarized and 15.3 nm for π-polarized. The emission spectra had inhomogeneous broadening; the maximum emission cross-section was 7.50 × 10−20 cm2 at 1065 nm with FWHM of 14.3 nm and 2.35 × 10−20 cm2 at 1346 nm with FWHM of 28.3 nm. The fluorescence lifetime at 1065 nm was 280.8 μs. The diode-pumped continuous-wave (CW) laser operation at 1.06 μm was achieved in Nd: CTGAS crystal, an output power of 1.77 W was obtained at the absorbed pump power of 5.5 W, the slope efficiency was 35.0 %, and the optical conversion efficiency was 32.2 %. A 1.35 μm CW laser operation with a slope efficiency of 12.0 % was realized in z-cut Nd: CTGAS crystal. • A bulk Nd: CTGAS crystal was grown by the Czochralski method. • The thermal behavior, polarized spectroscopy, and fluorescence lifetime were characterized systematically. • The efficient 1.06 μm and 1.35 μm CW laser operation was achieved in Nd: CTGAS crystal. • Nd: CTGAS crystal has application prospects in self-laser photoelastic modulators. [ABSTRACT FROM AUTHOR]

In this paper results concerning the fabrication of transparent (with 0.1% mol Yb 3+ ), translucent (with 0.5% mol Yb 3+ ) and opaque (up to 5% mol Yb 3+ ) Yb 3+ : MgAl 2 O 4 ceramics by hot pressing are presented. The alkoxotechnology of starting magnesium aluminate spinel nanopowder synthesis with homogeneous distribution of Yb ions is proposed. The structural properties of the prepared powders and ceramics were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET method. The optical transmittance, absorption and emission cross sections, and the upper level lifetime of the Yb 3+ :MgAl 2 O 4 ceramics were measured. [ABSTRACT FROM AUTHOR]

Titanium doped sapphire (Ti:Al 2 O 3 ) crystal fibers have been grown by the micro-pulling-down (μ-PD) method using different pulling rate in the range (0.1–0.5 mm/min). The present work has investigated the crystal growth, including diameter, bubbles defects and segregation properties. The fiber’s absorption and IR emission experiments are analyzed. The lifetime of Ti 3+ in the IR range obtained at room temperature is 3.1 μs. Moreover, the two blue emissions at 420 nm and 470 nm bands have been discussed. [ABSTRACT FROM AUTHOR]

Ho 3+ doped α-NaYF 4 single crystal with size of ∼∅10 mm × 100 mm was grown by an improved Bridgman method using KF as flux with the molar composition of raw materials NaF: KF: YF 3 : HoF 3 = 30: 18: 51: 1. The X-ray powder diffraction, transmission spectrum from 2500 nm to 8000 nm, absorption spectrum, emission spectrum by 640 nm excitation and fluorescence decay curves at 1190 nm and 2040 nm of the obtained single crystal were detected. The Judd–Oflet theory was applied to calculate the Judd–Oflet intensity parameters Ω 2,4,6 , radiative transition rate, branching ratio, radiative lifetime according to its measured absorption spectrum. The calculated maximum emission cross section by McCumber theory of Ho 3+ doped α-NaYF 4 crystal for ∼1.2 μm and ∼2.0 μm reached 0.42 × 10 −20 cm 2 and 0.69 × 10 −20 cm 2 , respectively. The gain cross section spectra were calculated based on the absorption and emission cross section spectra. In the meantime, the fluorescent lifetime at 1190 nm and 2040 nm were also estimated to be 3.21 ms and 18.12 ms from their decay curves. The Ho 3+ doped α-NaYF 4 single crystal with ∼90% high transmittance in wide range of 300–8000 nm and long lifetime of fluorescence may be considered as a potential candidate for applications in mid-infrared optical devices. [ABSTRACT FROM AUTHOR]

A crystal of Nd 3+ :Sr 6 YSc(BO 3 ) 6 was grown successfully by the top-seeded solution growth method. The average laser-induced damage thresholds are 1.76 GW/cm 2 for (0 0 1) face and 1.47 GW/cm 2 for (1 0 0) face at 1064 nm radiation, respectively. The average Vickers hardness of (1 0 0) and (0 0 1) faces are 629 and 545 N/mm 2 , respectively. The thermal expansion coefficients are 12.3 × 10 −6 K −1 along a -axis and 9.39 × 10 −6 K −1 along c -axis, respectively. The thermal conductivity is about 2.3 W/m K at room temperature. The polarized spectral properties were investigated in detail. Based on the Judd–Ofelt theory, the intensity parameters were obtained. The results show that Nd 3+ :Sr 6 YSc(BO 3 ) 6 crystal is a potential laser crystal. [ABSTRACT FROM AUTHOR]

Nd 3+ :Ba 3 Gd 2 (BO 3 ) 4 single crystal of sized ∅20 mm × 20 mm was grown by the Czochralski technique. The effective segregation coefficient of Nd 3+ in Ba 3 Gd 2 (BO 3 ) 4 crystals was measured to be 1.147. A series of thermal properties, including specific heat, the average linear thermal expansion coefficient, thermal diffusivity and thermal conductivity, were systematically determined as a function of temperature. The thermal conductivity along a , b and c -axes increases with increasing temperature. The room temperature polarized absorption spectrum was obtained over the range of 330–1000 nm, together with the room temperature fluorescence spectrum. The spectral parameters of the crystal were calculated by using the Judd–Ofelt (J–O) theory. The fluorescence lifetime is 80.58 μs and the fluorescence quantum efficiency is η c = 43.8%. A large FWHM value, moderate absorption cross-section and high thermal conductivity show that Nd 3+ :Ba 3 Gd 2 (BO 3 ) 4 crystal holds promise as a useful solid state laser material. [ABSTRACT FROM AUTHOR]

Highlights: [•] Sr6ErSc(BO3)6 crystal was grown successfully by TSSG method from a Li6B4O9 flux. [•] Sr6ErSc(BO3)6 crystal has good thermal and spectral properties. [•] Sr6ErSc(BO3)6 crystal is a potential laser material for 1.55μm laser. [ABSTRACT FROM AUTHOR]

Abstract: Yb3+ doped Sc2O3 and (Y0.9Sc0.1)2O3 transparent ceramics were fabricated by solid-state reaction and sintered in H2 atmosphere. The effects of Y2O3 on Yb:Sc2O3 ceramics were investigated. Y2O3 can inhibit the excessive grain growth in Yb:Sc2O3 ceramics, and increase the transparency effectively. The lattice parameter of Yb:(Sc0.9Y0.1)2O3 ceramics became larger due to the introducing of Y3+ ions. The gain cross-sections (σ g) were evaluated with different β values. The energy level diagrams were calculated based on the absorption and emission spectra, Yb:(Y0.9Sc0.1)2O3 ceramics exhibits a large ground-state splitting of 2F7/2. Furthermore, the emission bands of Yb:(Sc0.9Y0.1)2O3 ceramics are inhomogeneously broadened compared to Yb:Sc2O3 ceramics. Broad emission bandwidths of Yb:(Sc0.9Y0.1)2O3 ceramics are favorable for the generation of ultrashort pulse laser in mode-locked operation. [Copyright &y& Elsevier]

Abstract: A large and transparent Li3Ba2Yb3(MoO4)8 crystal has been grown from a Li2MoO4 flux by the top seeded solution growth (TSSG) method. The absorption and fluorescence spectra of the crystal have been described consistently with the anisotropic character of the monoclinic phase. The relative energies of the Yb3+ stark levels have been determined based on the room temperature absorption and low temperature fluorescence spectra. The absorption cross sections at 977nm are calculated to be 1.90, 2.71 and 1.09×10−20 cm−2 and the emission cross sections at 1002nm are calculated to be 1.18, 3.45 and 1.50×10−20 cm−2 for E//X, E//Y and E//Z, respectively. [Copyright &y& Elsevier]

Abstract: Rhodamine (Rh6G) dye-silica core–shell nanoparticles (DSCSNPs) have been prepared by the controlled hydrolysis and condensation of single silica precursor tetraethylorthosilicate (TEOS) using the sol–gel method. Scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis reveal that dye molecules are entrapped in silica (SiO2) shell resulting into core–shell particles of ∼30nm diameter. These particles are also characterized by X-ray diffraction and Fourier transforms infrared spectroscopy. The results indicate that core–shell particles are all in spherical shape and have a narrow size distribution. The fluorescent and optical properties of core–shell particles have been investigated using fluorescence and UV–Visible absorption spectra. The photoluminescence in solid or liquid medium occurs at the same wavelength. The SiO2 shell restricts the leakage and photobleaching of dye efficiently. These core–shell nanoparticles are found to be highly luminescent and stable. [Copyright &y& Elsevier]

Abstract: Polarized spectroscopic properties of a Ho3+-doped LuLiF4 (Ho:LuLF) single crystal grown by the Czochralski method have been investigated as a promising material for 2μm and 2.9μm lasers. The Judd–Ofelt (J–O) model has been applied to the analysis of the polarized room temperature absorption spectra to establish the so-called J–O intensity parameters. Based on the calculated parameters, we determined the emission probabilities, branching ratio and radiative lifetime for the Ho3+ transitions from the excited state manifolds to the lower-lying manifolds. Ho:LuLF crystal shows long fluorescence lifetime of 5I7 manifold (16ms) and broad absorption and emission spectra, which exhibit strong polarization characteristics. Stimulated emission cross-sections spectra of the 5I6 →5I7 and 5I7 →5I8 transitions were derived and compared with those of the other well-known Ho3+-doped laser crystals. [Copyright &y& Elsevier]

Abstract: In this paper we report the growth and characterization of Nd:(Lu x Gd1− x )3Ga5O12 crystal for the first time. The polycrystalline materials were synthesized by conventional solid-state reaction. Single crystal with good optical quality was successfully obtained and the dimensions of the as-grown crystal were Ø21×30mm3. X-ray powder diffraction studies confirm that the Nd:(Lu x Gd1− x )3Ga5O12 crystal is isostructural with Gd3Ga5O12 with unit cell parameter of 1.2361nm which is less than that of Gd3Ga5O12 crystal (1.2376nm). The absorption and emission spectra of the crystal at room temperature have also been studied. Continuous-wave (CW) laser performance at 1.06μm has been demonstrated on the crystal. [Copyright &y& Elsevier]

Abstract: Transparent 1at% Nd3+:Y1.9La0.1O3 ceramics were fabricated with nanopowders prepared by carbonate coprecipitation method. The powder compacts were sintered in H2 atmosphere at 1550°C for 30h. The Nd3+:Y1.9La0.1O3 ceramics display uniform grains of about 50μm and high transparency. The highest transmittance of the ceramics reaches 67%. The strongest absorption peak is in the wavelength of 820nm with absorption cross section of 2.48×10−20 cm2. The absorption is still high at LD wavelength 806nm with absorption cross section of 1.78×10−20 cm2 and broad full width at half maximum (FWHM) of about 6.3nm. The strongest emission peak was centered at 1078nm with large stimulated emission cross section of 9.63×10−20 cm2 and broad FWHM of about 7.8nm. The broad absorption and emission bandwidth of Nd3+:Y1.9La0.1O3 transparent ceramics are favorable to achieve the miniaturized LD pumping apparatus and ultrashort modelocked pulse laser output, respectively. [Copyright &y& Elsevier]

Abstract: A new laser crystal Nd3+: (La,Sr)(Al,Ta)O3 (abbreviated as Nd3+:LSAT) has been grown by the conventional Czochralski method. The absorption and luminescence spectra of trivalent neodymium in Nd3+:LSAT crystal were measured at room temperature. The value of absorption and emission cross-section was calculated. The Judd–Ofelt analysis was applied to the crystal to get the phenomenological parameters (Ω i , i =2,4,6), the line strengths, the radiative transition rates, the branching ratios and the radiative lifetime. [Copyright &y& Elsevier]

Abstract: The Cr(0.1%),Yb(10%):GGG crystals have been grown by the Czochralski method. The chemical composition is: Yb0.33Gd2.47Cr0.005Ga5.2O12. There are no observed Yb3+ ions substituting Ga3+ ions, just like that of Yb:GGG crystals. The defects in Cr,Yb:GGG crystal were also investigated. The absorption and emission spectra of Cr,Yb:GGG crystal at room temperature have been measured. The O2 and H2 annealing effect of Cr,Yb:GGG crystal have been compared. Cr3+ can greatly weak the visible luminescence of this crystal. The Cr–Yb-codoped crystals may be potential materials for compact, efficient, high stability LD pumped solid state lasers. [Copyright &y& Elsevier]

Abstract: The spectral properties of Er3+/Yb3+ codoped tungsten–tellurite glasses are investigated based on the Judd–Ofelt and McCumber theories. The compositional dependence of intensity parameter Ω 2 is attributed to the covalency of Er–O bonds for TeO2–WO3–La2O3 and TeO2–WO3–Bi2O3 glasses while for TeO2–WO3–BaO glasses, Ω 2 is mainly determined by the asymmetry in the local structures around Er3+ ions. The fluorescence full width at half maximum (FWHM) and the peak emission cross-section (σ peak) of the 4I13/2 → 4I15/2 transition of Er3+ ions in different glass hosts have been compared. The results indicate that the tungsten–tellurite glass is a promising host material for 1.55μm broadband amplification. [Copyright &y& Elsevier]

Abstract: This paper reports the growth and spectroscopic characterization of Nd3+:Ca2Nb2O7 crystal. Nd3+:Ca2Nb2O7 crystal with dimension up to ∅15×40mm3 have been grown by Czochralski method. The absorption cross-section at 798nm and the emission cross-sections σ em at 1068nm are 2.95×10−20 cm2 and 6.204×10−20 cm2, respectively. The fluorescence lifetime is 103μs at 300K. [Copyright &y& Elsevier]