高功率钕玻璃激光三倍频脉冲时间波形的研究

基于目前国内规模最大的激光驱动器——“神光Ⅱ”八路基频光已经实现功率平衡运行，通过改变其中若干路三倍频系统各调谐量的偏离，对输出三倍频波形进行束与束之间的横向对比研究．研究发现，对于Ⅱ类-Ⅱ类偏振失配三倍频系统，在影响转换效率的三个调谐量中，偏振分配角失配△θp，对三倍频波形影响最大；在入射基频功率密度约为1．0GW／cm^2情况下，当三倍频系统三个调谐量都处在最佳匹配时，三倍频波形半峰全宽τ最小。研究工作为最终实现“神光Ⅱ”八路光束三倍频功率平衡输出提供了晶体调试的方法。

激光稳频的共焦法布里-珀罗干涉仪

针对多普勒激光雷达激光源短期频率漂移低于1 MHz的要求,设计了一种共焦干涉仪作为频率标准进行稳频。通过对三种不同材料制成的共焦法布里-珀罗(Fabry-Perot)干涉仪中心频率随温度漂移情况进行分析对比,选用零膨胀微晶玻璃材料制作共焦法布里-珀罗干涉仪,腔镜和隔离器通过光胶的方式进行组合,并且置于温控精度优于0.01 K的双层密封温控箱中。经过实验测量,共焦法布里-珀罗干涉仪的自由光谱范围为370 MHz,透射谱半峰全宽(FWHM)为1.7 MHz,精细度为220。采用该共焦干涉仪进行稳频,理论稳频精度可达0.15 MHz,满足激光多普勒雷达单频激光源的稳频要求。

大气到海洋激光通信信道仿真

详细分析了蓝绿激光穿过大气海洋信道的信道效应和物理特性,利用理论分析和蒙特卡罗模拟方法完成对光信道仿真。介绍了大气海洋激光通信蒙特卡罗模拟方法及计算步骤。研究了不同厚度云层对光束投影面积的展宽,和光脉冲穿过不同深度海水后的空间分布和时域信号波形,讨论了其不同的展宽机理,并对信道的噪声分布进行了分析。发现云层对光脉冲展宽作用在云层厚度500 m时达到饱和,信号能量的随机起伏随海水深度的增加而增大,但能量分布的半峰全宽并不增加,大气海洋的综合信道效应可以用时延滤波器进行建模。

CE3+对ER3+/Yb3+共掺TeO2-WO3-ZnO玻璃发光性能的影响

Ce3+ ions were introduced into the Er3+/Yb3+ -codoped TeO2-WO3-ZnO glasses, and the effect of Ce3+ on the emission properties at 1.5 mu m band and the upconversion luminescence of Er3+ in the glasses was investigated. With the increasing of Ce3+ concentration, the emission intensity of Er3+ at 1.5 mu m band increases firstly, and then decreases. The optimal doping concentration of Ce3+ is about 2.07 x 10(20)/cm(3). As for the Er3+ emission at 1.5-mu m band, the fluorescence lifetime decreases a little from 3.4ms to 3.0ms, while the full width at half maximum (FWHM) hardly changes with the increase of Cc 3+ concentration. Due to the effective cross relaxation between Ce3+ and Er3+ : Er3+ (I-4(11/2)) + Ce3+ (F-2(5/2)) -> Er3+ (I-4(13/2)) + Ce3+ (F-2(7/2)), the upconversion emission intensity of Er3+ is reduced greatly. But when Ce3+ -doping concentration is too high, the other cross relaxation between Ce3+ and Er3+ : Er3+ (4I(13/2)) + Ce3+ (F-2(5/2)) -> Er3+ (I-4(15/2)) + Ce3+ (F-2(7/2)) happens, which depopulates the I-4(13/2) level of Er3+ and results in the decrease of the emission intensity and fluorescence lifetime of Er3+ at 1.5 mu m band.

掺铒碲-钨-钠玻璃基质的光谱性质研究

制备了用于离子交换法制备光波导器件的掺铒碲-钨-钠玻璃基质。应用扎得-奥菲而特(Judd—Ofelt)理论计算了玻璃样品的三个强度参量，由强度参量计算了Er^3+离子的自发跃迁几率、荧光分支比等光谱参量；应用麦克库玻(McCumber)理论，计算了Er^3+离子在1．5μm的受激发射截面，荧光测试发现Er^3+离子的荧光半峰全宽可达65nm。比较了Er^3+离子在不同玻璃基质中的光谱特性。结果表明，Er^3+离子在碲-钨-钠玻璃中具有较高的受激发射截面和较宽的荧光半峰全宽，可以用于宽带光波导器件的制备。

Effect of alkaline-earth metal composition on spectroscopic properties of Er3+ in fluorophosphate glasses

Optical spectroscopic properties of Er3+-doped alkaline-earth metal modified fluoropho sphate glasses have been investigated experimentally for developing broadband fiber and planar amplifiers. The results show a strong correlation between the alkaline-earth metal content and the spectroscopic parameters such as absorption and emission cross sections, full widths at half-maximum and Judd-Ofelt intensity parameters. It is found that strontium ions could have more influences on the Judd-Ofelt intensity parameters and the absorption and emission cross sections than other alkaline-earth metal ions such as Mg2+, Ca2+, Ba2+. The sample containing 23 mol% strontium fluoride exhibits the maximum emission cross section of 7.58 x 10(-21) cm(2), the broadest full width at half-maximum of 65 nm and the longer lifetime of 8.6 ms among the alkaline-earth metal modified fluorophosphates glasses studied. The Judd-Ofelt intensity parameter Omega(6)s, the emission cross sections and the full widths at half-maximum in the Er3+-doped fluorophosphate glasses studied are larger than in the silicate and phosphate glasses.

Thermal stability and spectroscopic properties of Er3+-doped niobium tellurite glasses for broadband amplifiers

Three Er3+-doped tellurite glasses with compositions of 70TeO(2)-30ZnO, 70TeO(2)-20ZnO-10Nb(2)O(5) and 70TeO(2)-20ZnO-5BaO-5Nb(2)O(5) have been investigated for developing fiber and planar broadband amplifiers and lasers. The optical spectroscopic properties and thermal stability of Er3+-doped tellurite glasses have been discussed. The results show that the incorporation of Nb2O5 increases the thermal stability of Er3+-doped tellurite glasses significantly, Er3+-doped niobium tellurite glasses 70TeO(2)-20ZnO-10Nb(2)O(5) and 70TeO(2)-20ZnO-5BaO-5Nb(2)O(5) exhibit the good thermal stability (DeltaT > 150degreesC), the large emission cross-section (>10 x 10(-21) cm(2)) and broad full width at half maximum (similar to65 nm), will be preferable for broadband Er3+-doped fiber amplifiers. (C) 2004 Elsevier B.V. All rights reserved.

977nm抽运下掺铒碲酸盐基氧卤玻璃的光谱特性

研究了掺铒TeO2-ZnO-PbCl2碲酸盐基氧卤玻璃在977nm激光二极管抽运下的发光和上转换发光特性，结果发现除红外1．53μm^4I13.2→^4I15/2发光外(荧光半高宽高达69nm)，该玻璃还存在很强的^2H11/2→^4I15/2(527nm)，^4S3/2→^4I15/2(549nm)和^4R9/2→^4I15/2(666nm)可见上转换发光．应用Judd-Ofelt理论计算得到玻璃强度参数Ω1(t=2，4，6)分别为Ω2=5．87×10^20cm^2,Ω4=2．08×10^2-cm^2，

Near infrared broadband emission from bismuth-dysprosium codoped chalcohalide glasses

We investigate the broadband infrared emission of bismuth doped and bismuth/dysprosium codoped chalcohalide glasses. It is found that the bismuth/dysprosium codoping can drastically enhance the fluorescence as compared with either bismuth or dysprosium doped glasses. Meanwhile, the full width at half maximum of bismuth/dysprosium codoped glasses is over 170 nm, which is the largest value among all the reported rare-earth doped chalcohalide glasses. An ideal way for energy consumption between bismuth and dysprosium ions is supposed. Such improved gain spectra of both bismuth and dysprosium ions may have potential applications in developing broadband fibre amplifiers.

Ultrabroadband infrared luminescence and optical amplification in bismuth-doped germanosilicate glass

This letter reports the ultrabroadband infrared luminescence from 1000- to 1700-nm wavelength range and demonstrate optical amplification at the second optical communication window in a novel bismuth-doped germanosilicate glass. The full-width at half-maximum of the luminescence is about 300 mn and the optical gain is larger than 1.37 within the wavelength region from 1272 to 1348 nm with pump power 0.97 W. This material could be useful to fabricate ultrabroadband optical fiber amplifiers.

Effects of melting temperature on the broadband infrared luminescence of bi-doped and Bi/Dy co-doped chalcohalide glasses

Bismuth (Bi)-doped and Bi/Dy co-doped chalcohalide glasses are investigated as promising materials for amplifiers in optical communication. The samples synthesized at lower melting temperatures (MTs) are characterized by more intensified infrared emissions. With respect to the redox process of a liquid mixture at different MTs, we attribute an emission at 1230 nm to low-valent Bi ions. The lower MT favors the formation of LVB ions, i.e. Bi+ or Bi2+, while the higher MT promotes the production of higher-valent Bi ions Bi3+. An enhanced broadband infrared luminescence with the full-width at half-maximum over 200 nm is achieved from the present Bi/Dy co-doped chalcohalide glasses.

Spectroscopic properties and Judd-Ofelt theory analysis of Dy3+ doped oxyfluoride silicate glass

Dy3+ doped oxyfluoride silicate glass was prepared and its optical absorption, 1.3 mu m emission, and upconversion luminescence properties were studied. Furthermore, the Judd-Ofelt [Phys. Rev. 127, 750 (1962); J. Chem. Phys. 37, 511 (1962)] intensity parameters, oscillator strengths, spontaneous transition probability, fluorescence branching ratio and radiative lifetime were calculated by Judd-Ofelt theory, while stimulated emission cross section of H-6(9/2)+F-6(11/2)-> H-6(15/2) transition was calculated by McCumber theory [Phys. Rev. A. 134, 299 (1964)]. According to the obtained Judd-Ofelt intensity parameters Omega(2)=2.69x10(-20) cm(2), Omega(4)=1.64x10(-20) cm(2), and Omega(6)=1.64x10(-20) cm(2), the radiative lifetime was calculated to be 810 mu s for 1.3 mu m emission, whose full width at half maximum and sigma(e) were 115 nm and 2.21x10(-20)cm(2), respectively. In addition, near infrared to visible upconversion luminescence was observed and evaluated. The results suggest that Dy3+ doped oxyfluoride silicate glass can be used as potential host material for developing broadband optical amplifiers and laser applications.

Spectroscopic properties of fluorophosphate glass with high Er(3+)supercript stop concentration

Fluorophosphate glass with 4 mol.% ErF3 content was prepared. The different scanning calorimetry was conducted. Raman spectrum, infrared transmission spectrum, absorption spectrum were measured. Fluorescence spectrum and lifetime of emission around 1.53 mu m were measured under 970 nm laser diode excitation. The metaphosphate content in the composition is limited, but the maximum phonon energy of glass amounts to 1290 cm- 1, and is comparatively high. The full width at half maximum is about 56 nm, and is wider than for most of the materials investigated. The measured lifetime of I-4(13/2) -> I-4(15/2) transition, contributed by the high phonon energy, inefficient interaction of Er3+ ions, and low water content, amounts to no less than 7.36 ms though the Er3+ concentration is high. This work might provide useful information for the development of compact optical devices.

Ultrabroad infrared luminescences from Bi-doped alkaline earth metal germanate glasses

We report on ultrabroad infrared (IR) luminescences covering the 1000-1700-nm wavelength region, from Bi-doped 75GeO(2) 20RO-5Al(2)O(3) 1B(2)O(3) (R = Sr, Ca, and Mg) glasses. The full width at half-maximum of the IR luminescences excited at 980 nm increases (315 -> 440 -> 510 nm) with the change of alkaline earth metal (Mg2+ -> Ca2+ -> Sr2+). The fluorescence lifetime of the glass samples is 1725, 157, and 264 mu s when R is Sr, Ca, and Mg, respectively. These materials may be promising candidates for broad-band fiber amplifiers and tunable laser resources.

Transparent Ni2+-doped lithium-alumino-silicate glass-ceramics for broadband near-infrared light source

Broadband infrared luminescence centred at around 1300 nm with full-width at half maximum of about 342 nm was observed from transparent Ni2+-doped lithium-alumino-silicate glass-ceramics embedded with beta-eucryptite crystallines. The room temperature fluorescent lifetime was 98 mu s. The transparent glass-ceramics may have potential applications in a widely tunable laser and a super-broadband optical amplifier for optical communications.