A high-performance LED-side-pumped two-rod Nd,Ce:YAG laser with continuous-wave(CW) and acousto–optical(A-O) Q-switched operation is demonstrated in this work. A symmetrically shaped flat–flat cavity with two identi...A high-performance LED-side-pumped two-rod Nd,Ce:YAG laser with continuous-wave(CW) and acousto–optical(A-O) Q-switched operation is demonstrated in this work. A symmetrically shaped flat–flat cavity with two identical LEDside-pumped laser modules is employed for power scalability. In the CW regime, the maximum output average power of laser at 1064 nm is 4.41 W, corresponding to a maximum optical conversion efficiency of 5.3% and a slope efficiency is 12.4%. In the active Q-switched regime, the pulse energy of laser reaches as high as 0.89 m J at a repetition rate of 800 Hz with a pulse width of 457.2 ns, the corresponding highest peak output power is 1.94 k W and the M~2 factor is measured to be about 8.8. To the best of the authors' knowledge, this is the first demonstration and the highest performance of a CW LED-side-pumped two-rod laser Nd,Ce:YAG with Watt-level output reported so far.展开更多
YAG： Ce^3 ＋ phosphor particles were prepared using polyacrylamide gel method. The structure evolution of powders during annealing process was followed by X-ray diffraction determination. It is found that some interm...YAG： Ce^3 ＋ phosphor particles were prepared using polyacrylamide gel method. The structure evolution of powders during annealing process was followed by X-ray diffraction determination. It is found that some intermediate phases, including θ-Al2O3, YAM and YAP, are formed when calcining polyacrylamide gel, however, the pure YAG phase can be formed directly when calcining polyacrylamide gel with α-Al2O3 as seed crystal. These facts show that the existence of α- Al2O3 seed crystal can block the formation of θ-Al2O3, YAM and YAP, and accelerate its reaction with Y2O3 to form YAG phase directly at lower temperature. The emission peak of prepared YAG ： Ce^3 ＋ phosphor is wide with maximum at 550 nm and the exitation band has two peaks, the major one is around at 460 nm, which matches the blue emission of GaN LED and is suitable for the assemble of white LED. Some fluxes can enhance the photoluminescence intensity of phosphor particles, that can be attributed both to the improvement of crystallization processes of YAG and to the stabilization of trivalence cerium ion in YAG：Ce^3 ＋.展开更多
Ce,Gd：YAG transparent ceramic was prepared by tape casting and solid state reaction method. Meanwhile, its crystal structure, chemical state and luminous properties were discussed. The prepared samples are identified...Ce,Gd：YAG transparent ceramic was prepared by tape casting and solid state reaction method. Meanwhile, its crystal structure, chemical state and luminous properties were discussed. The prepared samples are identified as pure garnet structure by the XRD results. The valence states of tetravalent and trivalent Ce ions were identified distinctly by X-ray photoelectron spectroscopy. A strong broad band yellow emission was found in photoluminescence（PL） spectra. The quantum yield reached 90.2% at room temperature. When collaborated with a 1.0 mm × 1.0 mm flip-chip, a luminous efficiency（LE） as high as 116.5 lm/W with a correlated color temperature（CCT） of 6627 K at a power dissipation of 1.13 W at 350 m A was demonstrated, indicating that Ce,Gd：YAG transparent ceramics had a promising potential for high power white light-emitting diodes.展开更多
The passively Q-switched and mode-locked（QML） characteristics in a diode-pumped Nd∶GdVO4 laser with Cr4+∶YAG saturable absorbers have been demonstrated. A maximum average output power of 710mW has been obtained in...The passively Q-switched and mode-locked（QML） characteristics in a diode-pumped Nd∶GdVO4 laser with Cr4+∶YAG saturable absorbers have been demonstrated. A maximum average output power of 710mW has been obtained in the QML laser. The maximum energy of a single Q-switched pulse is 52.5μJ, with the corresponding pulse width of 30ns and the peak power of 1.75kW, at the incident pump power of 7.75W. The repetition rates of the Q-switched envelope and the mode-locked laser pulse are 16.7kHz and 680MHz, respectively.展开更多
Cerium and europium codoped yttrium aluminum garnet（YAG：Ce,Eu） nanophosphors were prepared by sol-gel method.We systematically explored the structure,composition,morphology and photoluminescence（PL） properties by...Cerium and europium codoped yttrium aluminum garnet（YAG：Ce,Eu） nanophosphors were prepared by sol-gel method.We systematically explored the structure,composition,morphology and photoluminescence（PL） properties by using X-ray diffraction,scanning electron microscope,high resolution transmission electron microscope,energy dispersive spectrometer,photoluminescence emission and excitation spectra techniques,and focused on clarifying the change of local structure surrounding Ce^3＋ ions by utilizing advanced quantitative ^27Al magic angle spinning nuclear magnetic resonance spectroscopy.The results show that the lattice constant slightly increases as the Ce^3＋ and Eu^3＋ ions incorporate,and the geometric distortion of local structure surrounding Ce^（3＋） activator introduced by the incorporated Eu^（3＋） coactivator causes the variation of crystal field,which results in red shift of Ce^3＋ PL emitting in YAG：Ce,Eu nanophosphor.Furthermore,the YAG：Ce,Eu nanophosphors could exhibit several sharp and narrow ^5D0 → ^7FJ（J = 1-4） emissions of Eu^3＋ ion besides the classic broad ^5d1 → ^4f（^2F（5/2）,^2F（7/2）） emissions of Ce^3＋ ion under near ultraviolet（UV） excitation.展开更多
Four Nd:CeF_(3) crystals doped with 0.1,0.5,1.0 and 2.0 wt.% Nd^(3+)are grown,their absorption and fluorescence spectra are measured.The absorption bands of Nd:CeF_(3 ) are much wider than that of Nd:YAG.The absorptio...Four Nd:CeF_(3) crystals doped with 0.1,0.5,1.0 and 2.0 wt.% Nd^(3+)are grown,their absorption and fluorescence spectra are measured.The absorption bands of Nd:CeF_(3 ) are much wider than that of Nd:YAG.The absorption peak at 353nm does not depend on Nd^(3+) concentration linearly and there exists no concentration quenching effect while Nd^(3+) concentration is less than 2.0wt.%.The fluorescence lifetime and the effective stimulated cross section are measured,respectively,as τ_(r)=300μs and σ_(c)=2.4 x 10^(-20) cm^(2).展开更多
KLN and Ce：Nd：KLN crystals were gown by Czochralski method and polarized into single ferroelectrics domain along c-axis. The properties of KLN and Ce：Nd：KLN crystals, such as Curie temperature, Raman spectra, expo...KLN and Ce：Nd：KLN crystals were gown by Czochralski method and polarized into single ferroelectrics domain along c-axis. The properties of KLN and Ce：Nd：KLN crystals, such as Curie temperature, Raman spectra, exponential gain coefficient （Г） and thin crystal sheet effect, were measured. The results showed that the two spectra resembling Ce：Nd：KLN crystal were of tetragonal tungsten bronze structure, the exponential gain coefficient of Ce：Nd：KLN crystal was higher than that of KLN crystals and Ce：Nd：KLN crystal had thin crystal sheet effect, for its exponential gain coefficient increasing with crystal sheet thinning. The thin crystal sheet effect of Ce：Nd：KLN crystal was also discussed.展开更多
We have generated a second-harmonic generation （SHG） of a Q-switched microchip Nd：YAG laser on the surface of a periodically poled LiNbO3 （PPLN） nonlinear crystal near the grazing incidence angle. Three individua...We have generated a second-harmonic generation （SHG） of a Q-switched microchip Nd：YAG laser on the surface of a periodically poled LiNbO3 （PPLN） nonlinear crystal near the grazing incidence angle. Three individual SHC waves as transmitted homogeneous, kthomogeneous and reflected radiations have been generated and their intensities are measured and characterized within a desirable range of about 10 different incidence angles of the Nd：YAG laser as pump source on the PPLN surface. The basic of surface nonlinear radiation is also investigated and similar results are calculated and extracted from the theory. Comparison between calculated and measured data shows that they are in good agreement with each other.展开更多
Diode end-pumped solid-state lasers have the potential to yield high quality laser beams with high efficiency for laser range finding and warning receiver applications as well as day and night military laser designati...Diode end-pumped solid-state lasers have the potential to yield high quality laser beams with high efficiency for laser range finding and warning receiver applications as well as day and night military laser designation systems. In this paper we presents theoretical calculations using Advanced Dynamics Professional LASCAD software and experimental studies for a high power pigtailed fiber diode laser module of 8 W operating at 808 nm with a specially designed high efficiency cooling system, end pumped high-efficiency Nd:YVO4 laser of 3 × 3 × 10 mm rod and overall cavity length of 44 mm. To the best of our knowledge a self Q-switching effects was generated in Nd:YVO4 laser by changing the cavity dimensions and the position of the intracavity KTP crystal at certain regime of operation for the first time, in which the cavity length is reduced to be 30 mm and the distance between Nd:YVO4 rod and KTP crystal is only 1mm. Self Q-switched laser pulse at 532 nm with high peak power of 96 W, pulse width of 88 ns at FWHM and repetition rate of 400 kHz was achieved. Experimental studies of a passive Q-switched Nd:YVO4 laser using Cr:YAG crystal with three different transmissions of 30%, 40% and 70% were investigated. Passive Q-switched laser pulse at 1064 nm and narrow line width of less than 1.5 nm with highest peak power of nearly 18 kW, short pulse width of less than 4 ns at FWHM and higher repetition rate of 45 kHz using Cr:YAG with transmission of 30% was achieved for the first time.展开更多
基金Project supported by the Fund from Nanjing University of Posts and Telecommunications,China(Grant Nos.JUH219002 and JUH219007)the Key Research and Development Program of Shandong Province,China(Grant No.2021CXGC010202)。
文摘A high-performance LED-side-pumped two-rod Nd,Ce:YAG laser with continuous-wave(CW) and acousto–optical(A-O) Q-switched operation is demonstrated in this work. A symmetrically shaped flat–flat cavity with two identical LEDside-pumped laser modules is employed for power scalability. In the CW regime, the maximum output average power of laser at 1064 nm is 4.41 W, corresponding to a maximum optical conversion efficiency of 5.3% and a slope efficiency is 12.4%. In the active Q-switched regime, the pulse energy of laser reaches as high as 0.89 m J at a repetition rate of 800 Hz with a pulse width of 457.2 ns, the corresponding highest peak output power is 1.94 k W and the M~2 factor is measured to be about 8.8. To the best of the authors' knowledge, this is the first demonstration and the highest performance of a CW LED-side-pumped two-rod laser Nd,Ce:YAG with Watt-level output reported so far.
文摘YAG： Ce^3 ＋ phosphor particles were prepared using polyacrylamide gel method. The structure evolution of powders during annealing process was followed by X-ray diffraction determination. It is found that some intermediate phases, including θ-Al2O3, YAM and YAP, are formed when calcining polyacrylamide gel, however, the pure YAG phase can be formed directly when calcining polyacrylamide gel with α-Al2O3 as seed crystal. These facts show that the existence of α- Al2O3 seed crystal can block the formation of θ-Al2O3, YAM and YAP, and accelerate its reaction with Y2O3 to form YAG phase directly at lower temperature. The emission peak of prepared YAG ： Ce^3 ＋ phosphor is wide with maximum at 550 nm and the exitation band has two peaks, the major one is around at 460 nm, which matches the blue emission of GaN LED and is suitable for the assemble of white LED. Some fluxes can enhance the photoluminescence intensity of phosphor particles, that can be attributed both to the improvement of crystallization processes of YAG and to the stabilization of trivalence cerium ion in YAG：Ce^3 ＋.
基金Supported by the Major Program for Research on LED of Chinese Academy of Science(KZCC-EW-106)the National Key Research and Development Program of China(2016YFB0701003)the Natural Science Foundation of Fujian Province(2015j01231)
文摘Ce,Gd：YAG transparent ceramic was prepared by tape casting and solid state reaction method. Meanwhile, its crystal structure, chemical state and luminous properties were discussed. The prepared samples are identified as pure garnet structure by the XRD results. The valence states of tetravalent and trivalent Ce ions were identified distinctly by X-ray photoelectron spectroscopy. A strong broad band yellow emission was found in photoluminescence（PL） spectra. The quantum yield reached 90.2% at room temperature. When collaborated with a 1.0 mm × 1.0 mm flip-chip, a luminous efficiency（LE） as high as 116.5 lm/W with a correlated color temperature（CCT） of 6627 K at a power dissipation of 1.13 W at 350 m A was demonstrated, indicating that Ce,Gd：YAG transparent ceramics had a promising potential for high power white light-emitting diodes.
文摘The passively Q-switched and mode-locked（QML） characteristics in a diode-pumped Nd∶GdVO4 laser with Cr4+∶YAG saturable absorbers have been demonstrated. A maximum average output power of 710mW has been obtained in the QML laser. The maximum energy of a single Q-switched pulse is 52.5μJ, with the corresponding pulse width of 30ns and the peak power of 1.75kW, at the incident pump power of 7.75W. The repetition rates of the Q-switched envelope and the mode-locked laser pulse are 16.7kHz and 680MHz, respectively.
基金Financial support from the NNSF of China(No.51171007 and 51271009)
文摘Cerium and europium codoped yttrium aluminum garnet（YAG：Ce,Eu） nanophosphors were prepared by sol-gel method.We systematically explored the structure,composition,morphology and photoluminescence（PL） properties by using X-ray diffraction,scanning electron microscope,high resolution transmission electron microscope,energy dispersive spectrometer,photoluminescence emission and excitation spectra techniques,and focused on clarifying the change of local structure surrounding Ce^3＋ ions by utilizing advanced quantitative ^27Al magic angle spinning nuclear magnetic resonance spectroscopy.The results show that the lattice constant slightly increases as the Ce^3＋ and Eu^3＋ ions incorporate,and the geometric distortion of local structure surrounding Ce^（3＋） activator introduced by the incorporated Eu^（3＋） coactivator causes the variation of crystal field,which results in red shift of Ce^3＋ PL emitting in YAG：Ce,Eu nanophosphor.Furthermore,the YAG：Ce,Eu nanophosphors could exhibit several sharp and narrow ^5D0 → ^7FJ（J = 1-4） emissions of Eu^3＋ ion besides the classic broad ^5d1 → ^4f（^2F（5/2）,^2F（7/2）） emissions of Ce^3＋ ion under near ultraviolet（UV） excitation.
基金Supported by the National Natural Science Foundation of China。
文摘Four Nd:CeF_(3) crystals doped with 0.1,0.5,1.0 and 2.0 wt.% Nd^(3+)are grown,their absorption and fluorescence spectra are measured.The absorption bands of Nd:CeF_(3 ) are much wider than that of Nd:YAG.The absorption peak at 353nm does not depend on Nd^(3+) concentration linearly and there exists no concentration quenching effect while Nd^(3+) concentration is less than 2.0wt.%.The fluorescence lifetime and the effective stimulated cross section are measured,respectively,as τ_(r)=300μs and σ_(c)=2.4 x 10^(-20) cm^(2).
文摘KLN and Ce：Nd：KLN crystals were gown by Czochralski method and polarized into single ferroelectrics domain along c-axis. The properties of KLN and Ce：Nd：KLN crystals, such as Curie temperature, Raman spectra, exponential gain coefficient （Г） and thin crystal sheet effect, were measured. The results showed that the two spectra resembling Ce：Nd：KLN crystal were of tetragonal tungsten bronze structure, the exponential gain coefficient of Ce：Nd：KLN crystal was higher than that of KLN crystals and Ce：Nd：KLN crystal had thin crystal sheet effect, for its exponential gain coefficient increasing with crystal sheet thinning. The thin crystal sheet effect of Ce：Nd：KLN crystal was also discussed.
文摘We have generated a second-harmonic generation （SHG） of a Q-switched microchip Nd：YAG laser on the surface of a periodically poled LiNbO3 （PPLN） nonlinear crystal near the grazing incidence angle. Three individual SHC waves as transmitted homogeneous, kthomogeneous and reflected radiations have been generated and their intensities are measured and characterized within a desirable range of about 10 different incidence angles of the Nd：YAG laser as pump source on the PPLN surface. The basic of surface nonlinear radiation is also investigated and similar results are calculated and extracted from the theory. Comparison between calculated and measured data shows that they are in good agreement with each other.
文摘Diode end-pumped solid-state lasers have the potential to yield high quality laser beams with high efficiency for laser range finding and warning receiver applications as well as day and night military laser designation systems. In this paper we presents theoretical calculations using Advanced Dynamics Professional LASCAD software and experimental studies for a high power pigtailed fiber diode laser module of 8 W operating at 808 nm with a specially designed high efficiency cooling system, end pumped high-efficiency Nd:YVO4 laser of 3 × 3 × 10 mm rod and overall cavity length of 44 mm. To the best of our knowledge a self Q-switching effects was generated in Nd:YVO4 laser by changing the cavity dimensions and the position of the intracavity KTP crystal at certain regime of operation for the first time, in which the cavity length is reduced to be 30 mm and the distance between Nd:YVO4 rod and KTP crystal is only 1mm. Self Q-switched laser pulse at 532 nm with high peak power of 96 W, pulse width of 88 ns at FWHM and repetition rate of 400 kHz was achieved. Experimental studies of a passive Q-switched Nd:YVO4 laser using Cr:YAG crystal with three different transmissions of 30%, 40% and 70% were investigated. Passive Q-switched laser pulse at 1064 nm and narrow line width of less than 1.5 nm with highest peak power of nearly 18 kW, short pulse width of less than 4 ns at FWHM and higher repetition rate of 45 kHz using Cr:YAG with transmission of 30% was achieved for the first time.
