激光二极管端面抽运2μm Tm,Ho:YLF连续激光器的激光特性

根据能量在Tm3 离子和Ho3 离子之间的传递过程,给出了Tm,Ho:YLF激光器准三能级的速率方程,讨论了能量传递上转换及激光下能级粒子再吸收对Tm,Ho:YLF激光器运转的影响.报道了激光二极管抽运的Tm,Ho:YLF激光器的输出特性,室温下,在抽运功率为2.8 W时,获得了346 mW的TEM00模激光输出,阈值功率为138 mW,最大光-光效率为12.1%,并且将晶体保持在3个不同的温度下,给出了激光输出功率随抽运功率变化的实验结果.理论与实验结果吻合得比较好.     

Synthesis and characterization of Mg2B2O5

Magnesium borate of the form Mg₂B₂O₅ has been prepared and its structural and thermal properties were studied using X-ray diffraction and differential thermal analysis. An investigation of the electrical and optical properties of Mg₂B₂O₅ system has been carried out. The electrical resistivity of the sample was measured in the temperature range of 170-400 K. The data analysis revealed an extrinsic nature of the conductivity with two impurity levels located at 0.13 and 0.71 eV in the temperature ranges of 170-230 K and 240-400 K, respectively. The optical transmission and reflection was recorded at 300 K in the incident photon energy range of 3.0-6.0 eV. The absorption coefficient data analysis revealed an indirect optical energy band gap of 4.73 eV. In addition, two impurity levels located at 3.43, and 4.49 eV were observed in the absorption spectra.     

水热法合成一维GdV1-xPxO4∶Tm纳米材料及其发光性能

以乙二胺四乙酸(EDTA)为模板剂,采用水热法,成功地合成一系列具有较大长径比的一维GdV1-xPxO4∶Tm蓝色纳米荧光粉。利用X射线衍射仪、扫描电镜、荧光光谱仪对产物的相结构、形貌和发光性能进行了分析。结果表明所得产物均具有明显的一维特征,随P含量的增加,产物的长径比增加,纳米棒逐渐变细。产物在未经焙烧的条件下,在278nm波长紫外光激发下发出强度较高的波长为478nm的明亮蓝光,掺P摩尔比,即x=0.4时,所得产物的发光强度最好。     

蓝色荧光材料GdVO4:Tm3+的燃烧法合成及表征

采用燃烧法合成了蓝色荧光纳米晶GdVO4:Tm3+粉体.利用X射线衍射(XRD)、扫描电镜(SEM)以及荧光光度计等方法对GdVO4:Tm3+的物相结构、形貌粒度、发光性质等进行了研究.结果表明:所得产物为单一的四方相结构,晶粒尺寸小于70nm.GdVO4:Tm3+能够被240～350nm的紫外光激发,在320nm波长紫外光激发下发出波长为472nm的明亮蓝光;退火温度为1000℃,Tm3+掺杂摩尔浓度在0.4%时得到的GdVO4:Tm3+纳米晶的发光特性最好.     

Fabrication of double-cladding Ho3+/Tm3+ co-doped Bi2O3–GeO2–Ga2O3–BaF2 glass fiber and its performance in a 2.0-μm laser

A novel double-cladding Ho³⁺/Tm³⁺ co-doped Bi₂O₃–GeO₂–Ga₂O₃–BaF₂ glass fiber, which can be applied to a 2.0-μm infrared laser, was fabricated by a rod-tube drawing method. The thermal properties of the glass were studied by differential scanning calorimetry. It showed good thermal stability and matching thermal expansion coefficient for fiber drawing when T_x−T_g > 193°C and the maximum difference of the thermal expansion coefficient is 3.55 × 10⁻⁶/°C or less. The 2.0-μm luminescence characteristics were studied using the central wavelength of 808 nm pump light excitation. The results show that when the concentration ratio of Ho³⁺/Tm³⁺ reaches 0.5 mol%:1.0 mol%, the maximum fluorescence intensity was obtained in the core glass, the emission cross section reached 10.09 × 10⁻²¹ cm², and the maximum phonon energy was 751 cm⁻¹. In this paper, a continuous laser output with a maximum power of 0.986 W and a wavelength of 2030 nm was obtained using an erbium-doped fiber laser as a pump source in a 0.5 m long Ho³⁺/Tm³⁺ co-doped glass fiber. In short, the results show that Ho³⁺/Tm³⁺ co-doped 36Bi₂O₃–30GeO₂–15Ga₂O₃–10BaF₂–9Na₂O glass fiber has excellent laser properties, and it is an ideal mid-infrared fiber material for a 2.0-μm fiber laser with excellent characteristics     

激光二极管抽运的Tm, Ho: YLF单模激光器

为了获得高效率、小型化、稳定性好的激光器,种子激光器由激光二极管抽运Tm, Ho: YLF微片获得单模输出.短腔的自由光谱区比较宽,易于选单纵模,微片厚度0.9mm,两端镀膜,构成微型谐振腔.微片置于杜瓦瓶中,采用液氮制冷的方式,在低温下工作,增加了输出激光的稳定性.利用光纤延时自拍法进行频率短期稳定度测量,得到单模激光器短期稳定度为2.6kHz/μs,利用示波器估测长期稳定度小于35MHz.获得2.067μm的单模输出,线宽小于40MHz.利用刀口法测量得到光束质量为1.082,最大单模输出功率为32.8mW,斜率效率达到25.2%,光-光转换效率达23.8%,功率输出不稳定性小于1%.     

Cr,Tm, Ho:YAG激光器输出的实验研究

为了研究Cr,Tm,Ho:YAG激光器输出脉冲能量和晶体温度的关系,利用有限元的方法计算了不同制冷温度和抽运功率情况下晶体内温度的分布,从而分析温度分布对激光实验输出的影响。控制制冷液温度在15℃、重频5Hz时,获得最大能量为217mJ的脉冲输出,斜效率约为1.4%;而重频10Hz时,最大单脉冲输出仅为56mJ,斜效率约为0.9%。结果表明,制冷温度和频率的增加都将大大增加激光的抽运阈值,同时降低输出效率。     

高平均功率室温运转闪光灯抽运Cr:Tm:Ho:YAG激光器

报道了氙灯抽运的2.1μm Cr:Tm:Ho:YAG激光器.室温下Cr:Tm:Ho:YAG为准三能级系统.振荡阈值高,掺杂离子问存在复杂的能量转移过程.采用优化掺杂浓度配比的激光晶体,长脉冲抽运,实现了室温下2.1 μm波长激光输出.采用了高漫反射陶瓷聚光腔,对有效抽运光谱带的反射率高达95%.冷却水温15℃条件下,重复频率10 Hz,获得最大平均功率23.5 w;重复频率5 Hz,获得最大激光脉冲能量2.58 J,最大斜率效率4.3%.     

2μm掺铥（Tm~（3＋））光纤激光器的实验研究

为了实现高效、紧凑、窄线宽的2μm激光输出,采用中心波长为790nm的LD激光器作为泵浦源端面泵浦掺铥光纤,半导体散热系统,光纤布拉格光栅（FBG）构成谐振腔的全光纤激光器。首先,我们采用一个光栅,光纤尾端采用4%的菲涅尔反射,将所有的光学元件熔接在一起后,我们获得了2μm的稳定输出。当泵浦电流为44A时,获得的最大输出功率为8.7W,斜率效率为29.4%,其线宽为4.5m,阈值功率为0.7W。当采用两个光栅构成谐振腔时,其线宽可窄至3nm左右,光斑质量可得到进一步的提高.实验结果表明：该激光器稳定性可靠、输出激光线宽较窄,功率较高,光斑质量好。     

Tm3+/Ho3+共掺碲酸盐玻璃的中红外发光及能量传递机理

用高温熔融法制备了Tm3+/Ho3+共掺碲酸盐玻璃(TeO2-ZnO-Na2O),根据测量得到的吸收光谱,应用Judd-Ofelt理论计算分析了玻璃样品中Ho3+离子的强度参数Ωt(t=2,4,6)、自发辐射跃迁几率A、荧光分支比β和荧光辐射寿命τrad等各项光谱参数。同时,测量得到了不同Ho3+离子掺杂浓度下玻璃样品的荧光发射谱。结果显示,在808nm抽运光激励下Tm3+/Ho3+共掺碲酸盐玻璃样品发射出较强的2.0μm中红外荧光。分析表明,较强的Ho3+离子中红外荧光来自于Tm3+/Tm3+离子间共振的能量传递过程,以及Tm3+/Ho3+离子间基于零声子和单声子辅助非共振的两部分能量传递过程。由此进一步计算得到了Tm3+/Tm3+、Tm3+/Ho3+离子间的能量传递微观速率、临界半径和声子的贡献。最后,计算分析了Ho3+…5I7→5I8能级间跃迁的2.0μm波段吸收截面、受激发射截面和增益系数。研究表明,Tm3+/Ho3+共掺TeO2-ZnO-Na2O玻璃可以作为2.0μm波段中红外固体激光器的潜在增益基质。