The Ho：YAP crystal is grown by the Czochralski technique. The room-temperature polarized absorption spectra of Ho：YAP crystal was measured on a c-cut sample with 1 at% holmium. According to the obtained Judd-Ofelt i...The Ho：YAP crystal is grown by the Czochralski technique. The room-temperature polarized absorption spectra of Ho：YAP crystal was measured on a c-cut sample with 1 at% holmium. According to the obtained Judd-Ofelt intensity parameters Ω2 = 1.42 × 10^-20cm^2, Ω4 = 2.92 ×10^-20 cm^2, and Ω6 =1.71 ×10^-20cm^2, this paper calculated the fluorescence lifetime to be 6 ms for ^5I7→^5Is transition, and the integrated emission cross section to be 2.24 × 10^-18 cm^2. It investigates the room-temperature Ho：YAP laser end-pumped by a 1.91-μm Tm：YLF laser. The maximum output power was 4.1 W when the incident 1.91-μm pump power was 14.4W. The slope efficiency is 40.8%, corresponding to an optical-to-optical conversion efficiency of 28.4%. The Ho：YAP output wavelength was centred at 2118 nm with full width at half maximum of about 0.8nm.展开更多
Output performance of a continuous-wave TIn：YAP laser pumped passively Q-switched Ho：YLF laser is demon- strated with a polycrystalline Cr2＋ ：ZnS as the saturable absorber. We compare the experimental results at t...Output performance of a continuous-wave TIn：YAP laser pumped passively Q-switched Ho：YLF laser is demon- strated with a polycrystalline Cr2＋ ：ZnS as the saturable absorber. We compare the experimental results at the three different distances L of the polycrystalline Cr2＋ ：ZnS saturable absorber to the output coupler. The pulse width almost remains constant for different L, when the incident pump power is changed in the range of 7.9 27.1 W. The shortest pulse duration of 33.3 ns for L = 105 mm and the highest average output power of 6.8 W for L = 5 mm are obtMned at the incident pump power of 27.1 W. The output wavelength of the passively Q-switched laser shifts to 2045.2nm from 2064.7nm in the cw operation. The beam quality factor of M2 is 1.2.展开更多
The 30 at.% Ho： BaY2F8 crystals were grown by the Czochralski method, and their spectroscopic properties are analyzed systematically by standard Judd–Ofelt theory. The Judd–Ofelt intensity parameters are estimated ...The 30 at.% Ho： BaY2F8 crystals were grown by the Czochralski method, and their spectroscopic properties are analyzed systematically by standard Judd–Ofelt theory. The Judd–Ofelt intensity parameters are estimated to be Ω2 =6.74 × 10^-20cm^2,Ω4 = 1.20 × 10^-20cm^2, and Ω6= 0.66 × 10^-20cm^2, and the fluorescence branching ratios and radiative lifetimes for a series of excited state manifolds are also determined. The emission cross sections with our measured infrared luminescence spectra, especially important for 4.1 μm, are calculated to be about 4.37 × 10^-21cm^2. The crystal quality is preliminarily tested through a mid-infrared laser emission experiment.展开更多
The Ho3＋/yb3＋ co-doped a-NaYF4 single crystal was grown successfully for the first time by a modified Bridgman method in which KF was used as assisting flux and a large temperature gradient （70-90℃ /cm） of solid-...The Ho3＋/yb3＋ co-doped a-NaYF4 single crystal was grown successfully for the first time by a modified Bridgman method in which KF was used as assisting flux and a large temperature gradient （70-90℃ /cm） of solid-liquid interface was adopted. Upconversion emissions at green -544 nm, red -657 and -751 nm were obtained under 980 nm laser diode excitation. The intensity at -544 nm was much stronger than those of -657 and -751 nm. The mechanisms of the upconversion emissions were investigated by studying the relationship between the upconversion intensity and pump power. The optimized Yb3＋ concentration was about 8.08moi% when Ho3＋ concentration was hold at about 1.0mol%. The results showed that Ho3＋/yb3＋ doped α-NaYF4 single crystal was a possible candidate upconversion material for the green solid-state laser.展开更多
A simple rate equation model for 2μm Tm,Ho:YLF laser is given to study laser dynamics. Under low pump power, the explicit formulae for the threshold pump power and the relation between output power and incident power...A simple rate equation model for 2μm Tm,Ho:YLF laser is given to study laser dynamics. Under low pump power, the explicit formulae for the threshold pump power and the relation between output power and incident power are obtained. The present model provides a straightforward procedure to design the laser resonator and the optical coupling system for optimization. At the same time, the experimental results are reported. At room temperature the slope efficiency is 22.4% and the typical lasing threshold is about 328mW. The theory is in good agreement with experiment.展开更多
A single crystal of Li3Ba2Ho3（WO4）8 was obtained from a flux of Li2WO4 under an air atmosphere. The structure of the pure crystal was determined by single-crystal X-ray diffraction method. It crystallizes in the mon...A single crystal of Li3Ba2Ho3（WO4）8 was obtained from a flux of Li2WO4 under an air atmosphere. The structure of the pure crystal was determined by single-crystal X-ray diffraction method. It crystallizes in the monoclinic system, space group C2/c with a = 5.240（4）, b = 12.790（10）, c = 19.247（15）, β = 91.921（15）°, V = 1289.1（18）3, Z = 2, Mr = 2773.09, Dc = 7.144 g/cm3, μ = 47.732 mm-1, Rint = 0.0693, F（000） = 2340, the final R = 0.0472 and wR = 0.1221 for 1535 observed reflections （I 2σ（I））. The Li3Ba2Ho3（WO4）8 has a high structure disorder with one 8f site shared by Li（1） and Ho ions with occupancy of 0.25 and 0.75, respectively. The fundamental structure is constituted by distorted square antiprisms Ho/Li（1）O8 with C1 symmetry, distorted Li（2）O6 octahedra and BaO10 polyhedra. The optical properties were investigated by IR and absorption spectroscopy, and the emission cross sections and gain cross sections of 5I7 → 5I8 of Ho3＋ were calculated.展开更多
Ho3＋/yb3＋ co-doped LiYF4 single crystals with various Yb3＋ concentrations and ,-~ 0.98 mol% Ho3＋ concentration are grown by the Bridgman method under the conditions of taking LiF and YF3 as raw materials and a tem...Ho3＋/yb3＋ co-doped LiYF4 single crystals with various Yb3＋ concentrations and ,-~ 0.98 mol% Ho3＋ concentration are grown by the Bridgman method under the conditions of taking LiF and YF3 as raw materials and a temperature gradient （40 ~C/cm-50 ~C/cm） for the solid-liquid interface. The luminescent performances of the crystals are investigated through emission spectra, infrared transmittance spectrum, emission cross section, and decay curves under excitation by 980 nm. Compared with the Ho3＋ single-doped LiYF4 crystal, the Ho3＋/yb3＋ co-doped tiYf4 single crystal has an obviously enhanced emission band from 1850 nm to 2150 nm observed when excited by a 980-nm diode laser. The energy transfer from Yb3＋ to Ho3＋ and the optimum fluorescence emission around 2.0 p-m of Ho3＋ ions are investigated. The maximum emission cross section of the above sample at 2.0 p.m is calculated to be 1.08 × 10-20 cm2 for the LiYF4 single crystal of 1-mol% Ho3＋ and 6-mo1% Yb3＋ according to the measured absorption spectrum. The high energy transfer efficiency of 88.9% from Yb3＋ to Ho3＋ ion in the sample co-doped by Ho3＋ （1 mol%） and Yb3＋ （8 tool%） demonstrates that the Yb3＋ ions can efficiently sensitize the Ho3＋ ions.展开更多
基金supported by the Program of Excellent Team in Harbin Institute of Technology of China
文摘The Ho：YAP crystal is grown by the Czochralski technique. The room-temperature polarized absorption spectra of Ho：YAP crystal was measured on a c-cut sample with 1 at% holmium. According to the obtained Judd-Ofelt intensity parameters Ω2 = 1.42 × 10^-20cm^2, Ω4 = 2.92 ×10^-20 cm^2, and Ω6 =1.71 ×10^-20cm^2, this paper calculated the fluorescence lifetime to be 6 ms for ^5I7→^5Is transition, and the integrated emission cross section to be 2.24 × 10^-18 cm^2. It investigates the room-temperature Ho：YAP laser end-pumped by a 1.91-μm Tm：YLF laser. The maximum output power was 4.1 W when the incident 1.91-μm pump power was 14.4W. The slope efficiency is 40.8%, corresponding to an optical-to-optical conversion efficiency of 28.4%. The Ho：YAP output wavelength was centred at 2118 nm with full width at half maximum of about 0.8nm.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61308009,61405047,and 50990301the Postdoctoral Science Foundation of China under Grant No 2013M540288+1 种基金the Fundamental Research Funds for the Central Universities under Grant Nos HIT.NSRIF.2014044 and HIT.NSRIF.2015042the Science Fund for Outstanding Youths of Heilongjiang Province under Grant No JQ201310
文摘Output performance of a continuous-wave TIn：YAP laser pumped passively Q-switched Ho：YLF laser is demon- strated with a polycrystalline Cr2＋ ：ZnS as the saturable absorber. We compare the experimental results at the three different distances L of the polycrystalline Cr2＋ ：ZnS saturable absorber to the output coupler. The pulse width almost remains constant for different L, when the incident pump power is changed in the range of 7.9 27.1 W. The shortest pulse duration of 33.3 ns for L = 105 mm and the highest average output power of 6.8 W for L = 5 mm are obtMned at the incident pump power of 27.1 W. The output wavelength of the passively Q-switched laser shifts to 2045.2nm from 2064.7nm in the cw operation. The beam quality factor of M2 is 1.2.
基金Project supported by the National Natural Science Foundation of China(Grant No.61275146)the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120002110066)the Special Program of the Co-construction with Beijing Municipal Government of China(Grant No.20121000302)
文摘The 30 at.% Ho： BaY2F8 crystals were grown by the Czochralski method, and their spectroscopic properties are analyzed systematically by standard Judd–Ofelt theory. The Judd–Ofelt intensity parameters are estimated to be Ω2 =6.74 × 10^-20cm^2,Ω4 = 1.20 × 10^-20cm^2, and Ω6= 0.66 × 10^-20cm^2, and the fluorescence branching ratios and radiative lifetimes for a series of excited state manifolds are also determined. The emission cross sections with our measured infrared luminescence spectra, especially important for 4.1 μm, are calculated to be about 4.37 × 10^-21cm^2. The crystal quality is preliminarily tested through a mid-infrared laser emission experiment.
基金This work was supported by the National Natural Science Foundation of China （No.51472125, No.51272109） and K. C. Wong Magna Fund in Ningbo University.
文摘The Ho3＋/yb3＋ co-doped a-NaYF4 single crystal was grown successfully for the first time by a modified Bridgman method in which KF was used as assisting flux and a large temperature gradient （70-90℃ /cm） of solid-liquid interface was adopted. Upconversion emissions at green -544 nm, red -657 and -751 nm were obtained under 980 nm laser diode excitation. The intensity at -544 nm was much stronger than those of -657 and -751 nm. The mechanisms of the upconversion emissions were investigated by studying the relationship between the upconversion intensity and pump power. The optimized Yb3＋ concentration was about 8.08moi% when Ho3＋ concentration was hold at about 1.0mol%. The results showed that Ho3＋/yb3＋ doped α-NaYF4 single crystal was a possible candidate upconversion material for the green solid-state laser.
文摘A simple rate equation model for 2μm Tm,Ho:YLF laser is given to study laser dynamics. Under low pump power, the explicit formulae for the threshold pump power and the relation between output power and incident power are obtained. The present model provides a straightforward procedure to design the laser resonator and the optical coupling system for optimization. At the same time, the experimental results are reported. At room temperature the slope efficiency is 22.4% and the typical lasing threshold is about 328mW. The theory is in good agreement with experiment.
基金supported by the National Natural Science Foundation of China(20971123,51002153,21007070,51102232,61106004 and 21103191)
文摘A single crystal of Li3Ba2Ho3（WO4）8 was obtained from a flux of Li2WO4 under an air atmosphere. The structure of the pure crystal was determined by single-crystal X-ray diffraction method. It crystallizes in the monoclinic system, space group C2/c with a = 5.240（4）, b = 12.790（10）, c = 19.247（15）, β = 91.921（15）°, V = 1289.1（18）3, Z = 2, Mr = 2773.09, Dc = 7.144 g/cm3, μ = 47.732 mm-1, Rint = 0.0693, F（000） = 2340, the final R = 0.0472 and wR = 0.1221 for 1535 observed reflections （I 2σ（I））. The Li3Ba2Ho3（WO4）8 has a high structure disorder with one 8f site shared by Li（1） and Ho ions with occupancy of 0.25 and 0.75, respectively. The fundamental structure is constituted by distorted square antiprisms Ho/Li（1）O8 with C1 symmetry, distorted Li（2）O6 octahedra and BaO10 polyhedra. The optical properties were investigated by IR and absorption spectroscopy, and the emission cross sections and gain cross sections of 5I7 → 5I8 of Ho3＋ were calculated.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51472125 and 51272109)the K.C.Wong Magna Fund in Ningbo University,China(Grant No.NBUWC001)
文摘Ho3＋/yb3＋ co-doped LiYF4 single crystals with various Yb3＋ concentrations and ,-~ 0.98 mol% Ho3＋ concentration are grown by the Bridgman method under the conditions of taking LiF and YF3 as raw materials and a temperature gradient （40 ~C/cm-50 ~C/cm） for the solid-liquid interface. The luminescent performances of the crystals are investigated through emission spectra, infrared transmittance spectrum, emission cross section, and decay curves under excitation by 980 nm. Compared with the Ho3＋ single-doped LiYF4 crystal, the Ho3＋/yb3＋ co-doped tiYf4 single crystal has an obviously enhanced emission band from 1850 nm to 2150 nm observed when excited by a 980-nm diode laser. The energy transfer from Yb3＋ to Ho3＋ and the optimum fluorescence emission around 2.0 p-m of Ho3＋ ions are investigated. The maximum emission cross section of the above sample at 2.0 p.m is calculated to be 1.08 × 10-20 cm2 for the LiYF4 single crystal of 1-mol% Ho3＋ and 6-mo1% Yb3＋ according to the measured absorption spectrum. The high energy transfer efficiency of 88.9% from Yb3＋ to Ho3＋ ion in the sample co-doped by Ho3＋ （1 mol%） and Yb3＋ （8 tool%） demonstrates that the Yb3＋ ions can efficiently sensitize the Ho3＋ ions.
