Laser-diode end-pumped Tm(3+):YAG eye-safe laser

The lasing characteristics of a laser-diode end-pumped Tm:YAG laser were investigated. We obtained a laser output power of 124 mW, a slope efficiency of 36%, and a threshold power of 77 mW with a 3% Tm-doped YAG crystal at room temperature. This lasing performance was improved when the crystal was cooled. The dependencies of both slope efficiency and threshold power on temperature were measured.     

掺镨聚合物光纤的光辐射特性

制备了Pr(DBM)3Phen掺杂的聚合物光纤,研究了Pr(DBM)3Phen在聚甲基丙烯酸甲酯(PMMA)中的吸收光谱和荧光光谱.根据修正的Judd-Ofelt理论,用吸收光谱计算镨离子在PMMA中的强度参量:Ω2=46.334×10-20 cm2,Ω4=18.897×10-20 cm2,Ω6=1.610×10-20 cm2.用该参量计算镨离子(3P0、1D2)激发态的辐射寿命及各能级之间的辐射跃迁几率和荧光分支比,同时计算了(3P0→3F2、1D2→3H4)受激发射截面.分析表明,Pr(DBM)3Phen掺杂的聚合物光纤有望发展为聚合物光纤放大器和激光器.     

YAG:Yb~(3+),Tm~(3+)纳米晶粉体的制备及其蓝色上转换发光

以稀土氧化物、硝酸铝为原料,采用溶胶-凝胶法合成了Yb3+、Tm3+共掺的钇铝石榴石(Y3Al5O12,YAG)纳米晶粉体。采用X射线衍射(XRD)确定了1200℃煅烧后的晶体粉为纯YAG结构,无杂质相,晶体尺寸约为90nm;该粉体在波长为980nm的半导体激光器激发下发射出中心波长为487nm的蓝色上转换荧光,对应于Tm3+离子的1G4→3H6的跃迁。发光强度和激发功率关系的研究揭示了其为双光子过程,Tm3+的激发态吸收及Tm3+、Yb3+间的交叉驰豫型能量传递和是该上转换发光的主要机制。     

Optical characterization of Nd (3+):AgBr

The luminescence of silver bromide crystals, doped with neodymium, was investigated over the visible and near-infrared spectral ranges. The emission, excitation, and absorption spectra were measured over a broad temperature range. The absolute luminescence quantum yield was estimated by comparing the luminescence with that of a neodymium-doped phosphate glass, for which the manufacturer gives a value of 0.4. The Judd-Ofelt analysis was applied to both materials, and transition rates, branching ratios, and quantum efficiencies were calculated for all the observed bands. Good agreement was obtained between theory and experiment.     

Passively Q-switched Tm(3+)-doped silica fiber lasers

By splicing on a length of Ho(3+)-doped silica fiber onto a diode-pumped double-clad Tm(3+)-doped silica fiber, stable passive Q switching of the Tm(3+)-doped silica fiber laser is demonstrated. The formation of Q-switched pulses was found to depend on both the length and the position of the Ho(3+)-doped silica fiber that was inserted into the fiber laser cavity. For stable Q-switched pulse generation, Ho(3+)-doped silica fiber lengths shorter than twice the absorption depth must be used. For long Ho(3+)-doped silica fiber lengths, randomly generated pulses are observed at operating wavelengths longer than 2090 nm, which are attributed to intracavity pumping of the Ho(3+)-doped silica fiber.     

Quasi-Resonant Nonlinear Absorption for Optical Power Limiting: solgel-Processed Er(3+)-Doped Multicomponent Silica Glass

We demonstrate optical power limiting by what we believe to be a new mechanism of nonlinear absorption, which involves a quasi-resonant ground-state absorption that is either phonon assisted or assisted by the presence of defect sites (tail absorption). Such a mechanism provides high transmittance at low intensity yet optical limiting under cw conditions. The sample used was a novel solgel-processed Er(3+)-doped multicomponent silica glass. In this system the nonlinear absorption process is achieved because the resonant excited-state ((4)I(13/2) ? (4)S(3/2)) absorption cross section is larger than the quasi-resonant ground-state ((4)I(15/2) ? (4)I(9/2)) absorption cross section.     

提拉法Tm:YAG晶体的生长缺陷研究

采用提拉法(CZ)生长了质量优异的Tm:YAG晶体.部分晶片在1000℃的空气气氛中退火25h.借助光学显微镜、扫描电子显微镜(SEM),结合化学腐蚀法,对Tm:YAG晶体退火前后(111)面的缺陷特征进行了研究. Tm:YAG晶体(111)面的位错腐蚀坑呈三角形. 在偏光显微镜下观察了退火前后Tm:YAG晶体(111)面的应力双折射.同时应用高分辨X射线衍射法测定了晶体的完整性.实验结果表明,长时间空气气氛下高温退火有效降低了晶体中总的位错密度,提高了晶体质量.     

水中微量矿物油污染的光纤荧光监测技术及应用研究

通过对水中矿物油的荧光光谱特性进行理论分析和实验研究,提出并实现了监测水中微量矿物油含量的光纤荧光测量系统,进行了系统性能测试和现场应用实验研究。实验结果表明：应用光纤传感与传输技术的荧光法矿物油测量仪器,其理论正确、设计方案合理,为水中石油污染监测提供了一个全新的技术手段。     

F-P光纤应力传感器研制

分析了F-P光纤应力传感器工作原理,提出了F-P光纤应力传感器的数学模型,设计了F-P光纤应力传感器弹性体结构、光电转换系统.F-P光纤应力传感器光源电路设计采用APC电路.APC电路由两个运算放大器和晶体管以及外围电路组成,采用背向光反馈自动偏置控制方式,即用半导体激光器组件中的PD光电二极管监测LD背向输出的光功率.对F-P光纤应力传感器进行了静态特性标定试验,试验结果表明,该传感器具有较高的测量精度,能够满足工程测量要求.     

Strong photoluminescence through up and down conversion in Tm(3+)/Ho(3+):LaOF nanoparticles

Efficient up and down frequency conversions in Tm(3+) and Ho(3+) doped LaOF tetragonal nanocrystals have been investigated. Bright fluorescence emissions are obtained in co-doped Tm(3+)/Ho(3+):LaOF tetragonal nanocrystals through UV and infrared excitation. Green florescence from doped Ho(3+) ions, which can be clearly seen with bared eyes, is obtained when Tm(3+) ion is excited. Specific mechanism of the cross relaxation between doped ions is explored through spectroscopic measurements in time and frequency domains. About 90% energy transfer efficiency is obtained when the weak radiative and nonradiative relaxations are neglected.     

光闸式光纤位移传感器

本文介绍了一种强度调制型光纤传感器-光闸式光纤位移传感器,推导出其调制函数关系式.通过实验表明,与传统的位移传感器相比,其具有精度高、重复性好、无滞后性等优点.引进了均匀光斑装置后能提高工作区域范围,该善线性度.增加了参考通道后有效地减小了光源波动及光纤抖动等干扰信号的影响,更加有利于其在工程中的实际应用.     

水中石油类污染物的光纤荧光在线测量技术研究

根据水中石油类污染物质的光谱特性,采用荧光光谱技术,结合光纤传感技术和CCD探测技术,研制了一种可用于现场测量水中石油类污染物质的荧光光谱测量仪器。鉴于现场环境的特殊性,设计了水中自动取样预处理系统,可以实现真正意义上的实时分析,方便了现场操作。通过现场实验和性能测试,证实了其可行性,可以对水中石油类污染物质进行现场测量,从而进行污染物质的定性识别与定量分析,为水中污染物质监测提供了新的技术手段。     

SrZnO_2:Eu~(3+)红色荧光体的SHS合成及荧光性能

采用自蔓延燃烧法合成了SrZnO2:Eu3+红色发光材料,采用X射线衍射谱、荧光光谱对样品进行了表征.结果表明,Eu3+成功掺入SrZnO2基质中,在基质中主要占据Sr2+不对称性格位,发射来源于5D0→7F2 613nm为主的红光,同时产生了较高能级激发态5D1→7FJ(J=0～2)的发射.     

Tm(3+)-Doped Tellurite Glass for a Broadband Amplifier at 1.47 num

Tm(3+)-doped tellurite glass is investigated as a host for a broadband amplifier at 1.47 mum. The Tm(3+) fluorescence spectrum, lifetime, and cross section in tellurite glass are compared with those in fluorozirconate glasses. The advantages of a Tm(3+)-tellurite amplifier, especially when it is employed in combination with an Er(3+)-tellurite 1.55-mum amplifier, are discussed.     

Emission properties of hydrothermal Yb(3+), Er(3+) and Yb(3+), Tm(3+)-codoped Lu2O3 nanorods: upconversion, cathodoluminescence and assessment of waveguide behavior

Yb(3+) and Ln(3+) (Ln(3+) = Er(3+) or Tm(3+)) codoped Lu(2)O(3) nanorods with cubic Ia3 symmetry have been prepared by low temperature hydrothermal procedures, and their luminescence properties and waveguide behavior analyzed by means of scanning near-field optical microscopy (SNOM). Room temperature upconversion (UC) under excitation at 980 nm and cathodoluminescence (CL) spectra were studied as a function of the Yb(+) concentration in the prepared nanorods. UC spectra revealed the strong development of Er(3+) (4)F(9/2) → (4)I(15/2) (red) and Tm(3+) (1)G(4) → (3)H(6) (blue) bands, which became the pre-eminent and even unique emissions for corresponding nanorods with the higher Yb(3+) concentration. Favored by the presence of large phonons in current nanorods, UC mechanisms that privilege the population of (4)F(9/2) and (1)G(4) emitting levels through phonon-assisted energy transfer and non-radiative relaxations account for these observed UC luminescence features. CL spectra show much more moderate development of the intensity ratio between the Er(3+) (4)F(9/2) → (4)I(15/2) (red) and (2)H(11/2), (4)S(3/2) → (4)I(15/2) (green) emissions with the increase in the Yb(3+) content, while for Yb(3+), Tm(3+)-codoped Lu(2)O(3) nanorods the dominant CL emission is Tm(3+) (1)D(2) → (3)F(4) (deep-blue). Uniform light emission along Yb(3+), Er(3+)-codoped Lu(2)O(3) rods has been observed by using SNOM photoluminescence images; however, the rods seem to be too thin for propagation of light.     

一种光纤化学二氧化碳传感器的研制

研究开发了一种基于指示剂的二氧化碳光纤化学传感器,采用具有高气体可透过性和低折射率的无定型聚四氟乙烯(Teflon AF)材料作为液芯波导管,高灵敏度微型CCD分光光度计作为检测器,溴百里酚蓝(BTB,bromothymol blue)和Na2CO3为指示剂缓冲溶液。在0～194 ppm的CO2浓度范围内,传感器最佳精度为±1.21ppm,响应时间(99％)约为2 min。传感器具有体积小,能耗低等特点,适于现场长期自动监测。     

Ce~(3+)掺杂YAG透明陶瓷的制备与光性能研究

采用高纯微米级商业原料(≥99.99%)α-Al2O3、Y2O3和CeO2,用固相反应法制备了0.3at%Ce3+∶YAG透明陶瓷.粉体经行星式球磨,陶瓷素坯在1750℃真空烧结10h,真空度10-3Pa,双面抛光后,厚度为1.2mm的透明陶瓷试样在可见光区500~900nm的直线透过率可达80%左右,光学均匀性良好.荧光光谱分析表明,发射峰位于500~700nm之间,这是Ce3+的特征发射.结果表明,Ce∶YAG透明陶瓷的发光性能与相应的单晶相当,有望作为闪烁材料应用于中低能量射线(α、β粒子等)的探测.     

Cw industrial rod YAG:Nd(3+) laser with an intracavity active bimorph mirror

A special type of resonator with an intracavity wide-aperture active mirror was built, and a concave spherical bimorph active corrector was investigated. An increase of laser beam quality by a factor of 2-2.5 was achieved in a multimode regime of laser generation with an intracavity-controlled mirror. It was shown that various radiation mode structures could be formed at the laser output and in the far-field zone.     

Passively Q-Switched Yb:YAG Laser with Cr(4+):YAG as the Saturable Absorber

By using a continuous-wave Ti:sapphire laser as a pumping source, we demonstrated a passively Q-switched Yb:YAG laser at room temperature with Cr(4+):YAG as the saturable absorber. We achieved an average output power of as much as 55 mW at 1.03 mum with a pulse width (FWHM) as short as 350 ns. The initial transmission of the Cr(4+):YAG has an effect on the pulse duration (FWHM) and the repetition rate of the Yb:YAG passively Q-switched laser. The Yb:YAG crystal can be a most promising passively Q-switched laser crystal for compact, efficient, solid-state lasers.     

Cr~(4+):YAG被动调Q Nd:YAG陶瓷激光器输出特性研究

本文对Cr~(4+):YAG被动调Q Nd:YAG陶瓷激光器的输出特性进行了理论和实验研究.在相同泵浦功率和不同输出耦合透过率条件下,实验测量了被动调Q陶瓷激光器的输出激光重复频率、平均输出功率以及单脉冲能量,并与理论计算结果进行了比较.研究结果表明,随着输出耦合透过率的增加,输出激光重复频率单调减小,而平均输出功率及单脉冲能量则呈现出先增加后减小的变化趋势,只是平均输出功率及单脉冲能量所对应的最佳输出耦合透过率会有所不同.