Growth, optical properties, and CW laser action of neodymium-doped gadolinium scandium aluminum garnet

Investigation of the congruent melting rare-earth aluminum garnet Gd3Sc2Al3O12(GADSCAG) has been made. The optimum crystal growth parameters for the undoped material are a rotation rate of 20 r/min and a growth rate of 4.6 mm/hr along thelangle111rangledirection. For Nd³⁺-doped crystals the linear growth rate is 2 mm/h. The optical properties of Nd:GADSCAG which are of interest for laser operation were also determined. The stimulated emission cross section of the 1.06-μ transition in Nd³⁺at room temperature is(3.2 pm 0.3) times 10^{-19}cm², the fluorescence lifetime is256 pm 8 mus at an Nd³⁺ion density of 1 atomic percent in the crystal and the integrated peak absorption cross section in the strongest pump band (0.81 μ) is3.8 times 10^{-19}cm², A comparison of the CW laser performance of identical ND:YAG and Nd:GADSCAG rods is presented.     

单管LD泵浦的高效紧凑连续绿光激光器

结合Nd：YVO4的偏振吸收和LD（激光二极管）的偏振性,设计了高效的自聚焦透镜耦合系统、利用激光晶体和倍频晶体构成激光谐振腔、KTP晶体的II类相位匹配,计算并分析了在存在热透镜情况下平-平固体激光腔的特性,研制出高效紧凑结构的全固态绿光激光器。激光器利用TEC精确控制激光晶体和KTP晶体的温度,当泵浦功率为4.8 W时,532nm输出功率为1.4 W,光-光转换效率达到30%,24小时不稳定性±2%。     

硼酸镧玻璃的结构和热学性能研究

通过高温熔融法制备了La_2O_3-B_2O_3-Zn O(简称LBZ)系微晶玻璃,利用差热分析(DSC)、红外光谱(IR)和X射线衍射(XRD)等测试手段,研究了LBZ微晶玻璃的玻璃形成区域、原子的配位状态和相组成。同时探讨了组分含量与微晶玻璃的热学性能、析晶性能之间的关系。结果表明:LBZ的玻璃形成区间(摩尔分数)La_2O_3为0~24.4%、B_2O_3为34%~78%、Zn O为0~63%;LBZ微晶玻璃的网络结构主要由[BO_3]和[BO_4]组成,La~(3+)作为网络修饰体存在于网络间隙中,Zn_2+作为中间体以[Zn O4]的形式处于网络结构之中或以[Zn O6]形式处于玻璃结构之外;LBZ玻璃经高温热处理后的主要晶相为La(BO_2)3和La BO_3;玻璃化转变温度随着La_2O_3和B_2O_3含量的增加而增加、随着Zn含量的增加而降低;La系玻璃的析晶激活能介于337~397 k J/mol,且随着La_2O_3含量的增加而增大。     

Silica-clad neodymium-doped lanthanum phosphate fibers and fiber lasers

We have fabricated a neodymium-doped phosphate glass fiber with a silica cladding and used it to form a fiber laser. Phosphate and silicate glasses have considerably different glass transition temperatures and softening points making it hard to draw a fiber from these two glasses. A bulk phosphate glass of composition (Nd/sub 2/O/sub 3/)/sub 0.011/(La/sub 2/O/sub 3/)/sub 0.259/(P/sub 2/O/sub 5/)/sub 0.725/(Al/sub 2/O/sub 3/)/sub 0.005/ was prepared and the resultant material was transparent, free from bubbles and visibly homogeneous. The bulk phosphate glass was drawn to a fiber while being jacketed with silica and the resultant structure was of good optical quality, free from air bubbles and major defects. The attenuation at a wavelength of 1.06 /spl mu/m was 0.05 dB/cm and the refractive index of the core and cladding at the pump wavelength of 488 nm was 1.56 and 1.46, respectively. The fibers were mechanically strong enough to allow for ease of handling and could be spliced to conventional silica fiber. The fibers were used to demonstrate lasing at the /sup 4/F/sub 3/2/-/sup 4/I/sub 11/2/ (1.06 /spl mu/m) transition. Our work demonstrates the potential to form silica clad optical fibers with phosphate cores doped with very high levels of rare-earth ions (27-mol % rare-earth oxide).     

Spectroscopic analysis and diode-pumped laser results of Nd:BaY/sub 2/F/sub 8/

Single crystals of monoclinic BaY/sub 2/F/sub 8/, doped with different Nd/sup 3+/ concentrations, were successfully grown by means of the Czochralski method. Here, we present a polarized infrared (IR) spectroscopic investigation and diode-pumped continuous-wave laser results in the 1 /spl mu/m wavelength region. Moreover for the first time 1.3 /spl mu/m laser emission has been characterized. Q-switching results in the 1-/spl mu/m region are also presented.     

Generation of blue light at 469 nm by efficient frequency doublingof diode-pumped Nd:YAG laser

Efficient operation of a diode-pumped Nd:YAG laser at 938.5 nm is reported. A continuous wave output power of 3.9 W is obtained. Single-pass frequency doubling in periodically poled KTiOPO₄ (KTP) delivered a power of 88 mW at 469 nm. By intracavity frequency doubling an output of 200 mW in the blue region is achieved     

Efficient diode-pumped CW and Q-switched single-mode fibre laser

We report the efficient operation an Nd3+-doped silica single-mode fibre laser pumped by a GaAlAs laser diode. A CW output power in excess of 1 mW at 1.088 ?m has been obtained with a slope efficiency of 33%. Q-switched operation of this device is also reported.     

半导体抽运的叠片热容激光器理论和实验研究

报道了半导体抽运的Nd:YAG叠片热容激光器的理论与实验研究,并用热容激光器的理论模型计算了在一定的工作时间和介质温升内激光输出特性,用Zemax软件对其抽运结构进行了模拟计算。实验中采用的4片Nd:YAG晶体尺寸均为63.5 mm×38.5 mm×7 mm,抽运平均功率约110 W,重复频率为10 Hz,占空比为0.2％,获得了最大19.1 W的1 064 nm激光输出,光光效率约17.4％。最后对两种抽运结构的叠片激光器进行了比较,提出了下一步的改进方案。     

Er:GSGG 晶体的光谱性质分析及激光特性模拟研究

测试和分析了Er:GSGG的吸收光谱和荧光光谱。应用Judd-Ofelt理论计算了Er3+的强度参数、自发辐射跃迁几率、能级寿命、荧光分支比和吸收截面。结果表明,Er3+在4I13/2和4I11/2能级有较长的能级寿命,在966nm和790nm处有较大的吸收截面,在2.79µm处有较大的积分发射截面值,数值模拟了在966nm泵浦下激光输出特性,在泵浦速率达到一定值时,有较高的量子效率。结果表明Er:GSGG有望成为2.79µm波段的理想激光晶体。     

高效激光染料DCM的调谐特性

实验研究了激光新染料DCM在不同溶剂、不同浓度时的激光特性,测量了它的调谐范围和峰值波长.指出在N_2激光泵浦情况下,DCM的激光转换效率可与若丹明6G相当.     

机载全固态激光器的设计与仿真技术研究

以机载应用为背景,对全固化激光器在机载光电探测系统中的应用关键技术进行了仿真计算和试验研究;以研究结果为依据,设计、调试出了全固化激光测距/照射系统,测试结果表明它的综合技术水平可以满足机载应用要求.在机载光电探测系统中采用全固化激光器,从根本上解决了过去采用灯泵激光器所引入的氙灯触发干扰、氙灯预燃干扰、储能电容高压脉冲工作等种种电磁干扰,可以大大改善机载激光测距/照射系统的电磁兼容性、可靠性和维修性.     

Spectroscopic and laser properties of Nd3+ in BIGaZLuTMnfluoride glass

The optical properties of Nd³⁺-doped fluoride BIGaZLuTMn glass have been investigated by using steady-state and time-resolved laser spectroscopy. Laser action has been obtained for the first time in this glass by flashlamp pumping. The influence of site-dependent effects on fluorescence lifetime and time-resolved stimulated emission has been proved     

Theoretical and experimental investigations of small-signal gainfor a diode-pumped Q-switched Cr:LiSAF laser

We present a theoretical model proving that up-conversion and thermal quenching of fluorescence strongly limit small-signal gain in a CW pumped Cr:LiSAF laser. We have a good agreement with experimental measurements of small-signal gain obtained with a new simple method. We have then optimized the gain in a Cr:LiSAF laser pumped by two 400-mW red diodes. The highest gain, 1.11 at 600 mW of absorbed pump power, is obtained if the pump spot is circularized inside the crystal and if the Cr:LiSAF is pumped on both sides. In Q-switched operation, this laser produces tunable pulses (up to 6.5 μJ at 10 kHz) between 800 and 900 nm     

Spectroscopic and laser characteristics of Er,Cr:YSGG

The spectroscopic and laser properties of crystal Er,Cr:YSGG are discussed and it is shown that excitation is efficiently transferred from chromium to erbium. Laser operations at 2796 nm are achieved with much lower thresholds than in other erbium-doped crystals     

2.5 GHz and 5 GHz harmonic mode-locking of a diode-pumped bulkerbium-ytterbium glass laser at 1.5 microns

Third-order harmonic mode locking of a diode-laser pumped bulk Er:Yb:glass laser by frequency modulation with a lithium niobate modulator is reported. Stable pulses at a repetition rate of 2.5 and 5 GHz with a pulse duration down to 9.6 ps are obtained. The average output power is 3 mW, the pulse peak power is 120 mW at 2.5 GHz repetition rate, and the pulses are approximately 1.4 times transform limited. The pulse duration can be increased up to 30 ps by decreasing the mode-locker drive power     

Optical spectroscopy and diode-pumped laser performance ofNd3+ in the CNGG crystal

We have exploited the broad absorption and emission bandwidth of the laser crystal Ca₃(NbGa)_2-xGa₃O₁₂ doped with Nd³⁺ to develop a tunable and mode locked diode-pumped 1.06 μm laser. We also present the fluorescence and excitation spectra at different crystal temperatures from 10 to 298 K. The spontaneous transition probabilities, the branching ratios, and the radiative lifetime are calculated by means of the Judd-Ofelt theory and compared with the experimental results. The stimulated emission cross-sections of the most important transitions have been calculated and compared with laser results. Employing a 2-W laser diode as a continuous-wave pump source, we have been able to tune the emission wavelength in the range 1053-1074 nm. Active mode-locking yielding pulses of 9.6, 18, and 19.7 ps at the three main emission peaks of 1058.6, 1061.2, and 1065.3 nm, respectively. was also demonstrated     

A new exact and efficient numerical matrix theory of complicated laser structures: properties of asymmetric phase-shifted DFB lasers

A numerical matrix method is developed which permits the analysis of very complicated laser structures. It is applied to different laser structures including asymmetric phase-shifted DFB-lasers both with abrupt and extended phase-shift sections. Results for modal behavior, threshold gain differences and power distribution are presented.     

Synthesis and luminescence properties of lithium,zinc and scandium 1-(2-pyridyl)naphtholates

1-(2-Pyridyl)naphth-2-ol (pynH) was synthesized from 2-bromopyridine and 1-bromo-2-hydroxynaphthalene and structurally characterized. This ligand and the known 2-(2-pyridyl)phenol (ppH) ligand were reacted with LiN(SiMe₃)₂, ZnEt₂ and Sc[N(SiMe₃)₂]₃ to prepare the new luminescent complexes Li(pp), Li(pyn), Zn(pyn)₂, Sc(pp)₃, Sc(pyn)₃ and known Zn(pp)₂. Photoluminescent (PL) spectra of the compounds contained a single broad band with a maximum at 447–473 nm. The OLED devices with a configuration of ITO/TPD/complex/Bath/Yb gave blue–green emission. The emission spectra of these devices resembled the PL spectra; however, the bands of electroluminescence (EL) were shifted 20–40 nm to the long-wavelength side. A maximum current efficiency 15.3 cd/A and a power efficiency 8.12 lm/W at 100 cd/m² were measured for the device with the zinc luminophore Zn(pp)₂, whereas the highest luminance of 8300 cd/m² at 22.5 V was observed with the device with the scandium complex Sc(pp)₃. DFT calculations showed that the latter complex exhibited the lowest HOMO and the highest LUMO energy levels compared with the other investigated compounds. The calculated trends with respect to the influence of the metal and the ligand on the LUMO–HOMO gap agree well with the shifts of the electronic transitions observed in the PL spectra of the complexes.     

A unique and facile preparation of lanthanum ferrite nanoparticles in emulsion nanoreactors: Morphology,structure, and efficient photocatalysis

Lanthanum ferrite nanoparticles (LaFeO₃ NPs) with light absorption properties in the visible region were successfully synthesized in CTAB (cetyltrimethyl ammonium bromide) emulsion nanoreactors at room temperature. The morphology, size, structure, elemental composition, and optical properties of these particles were characterized by field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence (XRF), and ultraviolet–visible absorption (UV–Vis) spectroscopy. Through this method, highly crystalline and well-dispersed perovskite LaFeO₃ NPs with a phase-pure were successfully obtained. The band gap energy (E_g) of the LaFeO₃ NPs was calculated by UV-Vis spectroscopy at the wavelength of about 517 nm and is observed to have a value of 2.43 eV. The photocatalytic activities of LaFeO₃ NPs were evaluated by the degradation of toluidine blue O (TBO, used as a probe) dye under visible light irradiation, which exhibits a high photocatalytic TBO dye degradation activity as compared to the commercial P-25 titania powder. This phenomenon is due to smaller band gap energy and changing from bulk to nanostructure. The higher photocatalytic activity is also related to the photo absorption.     

若丹明6G乙醇溶液中566nm泵浦的高效可调谐激光输出

报道了使用 5 66nm波长的染料激光激发高浓度的若丹明 6G(R6G)乙醇溶液得到波长在 5 72nm -610nm的可调谐染料激光输出 ,光束发散角为 5mrad ,能量转换效率达到 10 %。比较了使用Nd :YAG激光倍频光 ( 5 3 2nm)与 5 66nm染料激光激励R6G乙醇溶液的不同结果。讨论了染料激光浓度调谐机理 ,并从染料溶液的吸收谱及激发谱讨论了染料溶液抽运光波长的选择。