Cd0.95Fe0.05Te能隙的温度和压力效应

采用金刚石对顶砧高压装置测量了半磁半导体Cd_(0.95)Fe_(0.05)Te光吸收边的压力效应,得到其一级和二级压力系数分别为α=8.2×10~(-11)eV/Pa和β=-7.7×10~(-21)eV/Pa~2;测量了不同温度下的Cd_(0.95)Fe_(0.05)Te吸收谱,得到其能隙温度系数为α=-4.4×10~(-4)eV/K。此外,在低温下发现了一个Fe~(2+)吸收峰,根据晶体场理论判定为Fe~(2+)的~5E→~3T_1跃迁吸收峰。     

干涉法测量Zn(SCN)_2·2H_2O晶体的压电系数和电光系数

用干涉法首次测量了Zn(SCN)_2·2H_2O晶体的全部压电系数和电光系数。结果为:d_(14)=-8.8,d_(25)=-15.8,d_(36)=1.2(×10~(-12)C/N);γ41=4.5,γ52=6.4,γ63=0.8(×10~(-12)m/V)。     

掺铈铌酸锶钡单晶在632.8nm处的高灵敏全息存储

报道了用低功北He-Ne激光器在掺铈铌酸锶钡中的高灵敏全息存贮,其最大光致折变△n_(max)=1.07×10~(-4)光致折变灵敏度s=8×10~(-4)cm~2/J,最大衍射效率可达78%.并对其光读出特性进行了研究.     

一种汽相外延Ga_xIn_(1-x)As的技术

本文描述了一种汽相外延Ga_xIn_(1-x)As的技术:在AsCl_3/Ga/In/H_2体系中,采用Ga/In合金源汽相生长Ga_xIn_1As。该方法具有外延层组分重复可控、均匀性好的特点;且易于获得高纯外延Ga_xIn_(1-xAs层。外延Ga_(0.47)In_(0.53)As电学参数最佳值已达:n300K=1.2×10~(15)cm~(-3),μ300K=9580cm~2/V·s;n77K=1.1×10~(15)cm~(-3),μ77K=3.82×10~4cm~2/V·s。     

测量光学参考腔稳定度的偏振法

报告一种测量光学参考腔稳定度的偏振方法。以稳定度为2×10~(-10)(采样时间0.01s)的He-Ne激光器用该法实际测量了一个参考腔的稳定度为1.3×10~(-9)。     

甲基氟远红外激光的斯塔克频移

本文对甲基氟(CH_3F)光泵远红外激光的斯塔克频移做了理论计算。指出用2.9×10~4～4.4×10~4伏/厘米的电场强度,有可能使甲基氟发射的远红外激光(496微米)与镁原子束的~3P_0→~3P_1跃迁共振,同时保证甲基氟的泵浦跃迁与 CO_2激光9P(20)线共振。预期可能的工作跃迁有四组:~QR(11,5,-11),~QQ(12,5,-11);~QR(11,6,-6),~QQ(12,6,-6);~QR(11,7,-3),~QQ(12,7,-3);~QR(11,8,0),~QQ(12,8,0)。     

发射深红色激光的Ho:YLF

报导了2％Ho:YLF在室温下~5S_2→~5I_7跃迁的激光工作。用闪光灯和染料激光器泵浦的实验获得λ=750毫微米振荡。用上述泵浦测试阈值分别为4焦耳/厘米和3×10~(-4)焦耳/厘米。750毫微米的Ho:YLF是四能级激光器,其受激发射截面为σ=9.7×10~(-19)厘米~2。     

TA7214P、TA7215P、TA7229P集成电路的功能与应用

TA7214P双通道音频功率放大集成电路(一)用途(1)通用双通道音频功率放大(2)大功率立体声收录机音频放大(二)特点(1)输出功率P_0(V_∞=13.2伏、R_L=4欧,总谐波失真THD≤10%)BTL型:P_0=15瓦(电路同TA7229P)双通道:P_(01)=4.8瓦×2(负载R_L=4欧)P_(02)=7.5瓦×2(负载R_L=2欧)     

MCT液相外延薄膜的生长和特性

用开管水平液相外延系统从富Te溶剂中生长了不同x值的MCT薄膜。经X射线衍射、Hall电学参数、红外光谱、扫描电镜、X射线能谱仪和电子通道花样分析测试,结果表明:外延薄膜表面平整,光学参数较好,纵向、横向组份均匀,晶体结构完整,电学参数较好,外延膜质量优良。短波材料(n型):载流子浓度3.54×10~(14)cm~(-3),迁移率1.63×10~4cm~2V~(-1)s~(-1);中波材料(n型):载流子浓度9.95×10~(14)cm~(-3),迁移率为1.76×10~4cm~2V~(-1)s~(-1);原生长波材料(n型):载流子浓度为2.15×10~(15)cm~(-3),迁移率2.00×10~4cm~2V~(-1)s~(-1)。     

He-Ne激光器研制中真空系统的改进

在He-Ne激光器的制作过程中,真空系统的好坏对器件性能有直接影响。 目前He-Ne激光器中普遍使用的He、Ne气体的纯度均在99.99％以上,即在He-Ne激光管中所含杂质气体分压强约为2×10~(-4)托,其中有害杂质气体分压强可能达到10~(-5)托的量级。因此,研制He-Ne激光器时要求真空系统动态能达到10~(-6)托,静态也要有够用的时间保持在10~(-5)托以上。     

Yb3+掺杂锌锗碲酸盐玻璃的热分析、光谱和激光性质

设计了组成为0．70TeO2-(0．20-x)ZnO-xGeO2—0．05La2O3-0．025K2O-0．025Na2O-0．01Yb2O3(摩尔分数x=0,0．05，0．10，0．15和0．20)的碲酸盐激光玻璃，测试了热学性质、吸收光谱、荧光光谱和荧光寿命。计算了Yb^3 离子的吸收截面、受激发射截面、荧光有效线宽等参数。结果表明，组成为0．70TeO2-0．20GeO2-0．05La2O3-0．025K2O-0．025Na2O的玻璃具有优于著名的碲锌钠(TZN)玻璃的热稳定性，高的受激发射截面(1．23pm^2)。长的荧光寿命(0．92ms)和宽的荧光有效线宽(77nm)。通过激光性能评价。最小抽运强度为0．98kW／cm^2，表明掺Yb^3 组份的碲酸盐玻璃是实现高能短脉冲可调谐激光器的理想增益介质。     

Er3+: Y0.5Gd0.5VO4激光晶体的生长和热学性质

用提拉法生长出Er3 : Y0.5Gd0.5VO4单晶,用电感耦合等离子体(ICP)光谱法测定晶体中Er3 原子数分数为0.83%,有效分凝系数为1.03.在30～1300℃测量了晶体a轴和c轴的热膨胀系数分别为2.08×10-6/℃,8.87×10-6/℃;测得晶体在25℃时的比热值为0.48J/(g·K).采用激光脉冲法测量了晶体的热扩散系数,并通过计算得出晶体的热导率,在25～200℃温度范围,晶体在<100方向上的热导率为6.1～4.9W/(m·K),在<001方向上的热导率为7.7～6.2W/(m·K).     

Emission cross section and fluorescence efficiency of Nd-pentaphosphate

The room-temperature cross sections for the Nd³⁺⁴F_{3/2}levels to the⁴I_{11/2}and⁴I_{9/2}manifolds (lower laser state and ground state, respectively) in NdP5O14are measured by two spectroscopic methods. A value for the largest cross section ofsigma(R_{1} - Y_{2}) = 1.7 times 10^{-19}cm²is found. The highest effective cross section, resulting from superposition of two lines at 1.051 μm, gives a laser gain per Nd ion which is about 2/3 of the maximum gain in YAG:Nd. The relative branching ratio into the⁴I_{11/2}and⁴I_{9/2}manifolds is 0.65:0.35. Comparison of the integrated cross sections with the measured lifetime for 1-percent Nd in LaP5O14indicates a combined efficiency <0.1 for the remaining transitions, namely radiative decay into the⁴I_{13/2}and⁴I_{15/2}manifolds and multiphonon quenching. A measurement of temperature dependence of fluorescence lifetime supports this last result.     

The effect of thermally induced gain gradients in solid statelasers

A dependence of the small-signal gain in solid-state lasers on the thermal loading is calculated. An average thermal power dependent gain reduction factor, η_g(𝒬), is defined in terms of the temperature coefficients of the laser gain curve, and the thermal conductivity of the laser rod. η_g(𝒬) arises from the shifts in the laser gain curve associated with the temperature gradients caused by optical pumping, and reduces the small-signal gain. The calculation of η_g(𝒬) for the specific cases of Nd:YAG and Nd;Cr:GSGG lasers indicates a reduction in the small-signal gain, from this mechanism alone, of 20-30% at high average power (200 W-cm^-3, thermal)     

Optical Gain and Spontaneous Emission in GaAsSb–InGaAs Type-II “W” Laser Structures

The modal gain, modal loss and spontaneous emission of a GaAsSb-based type-II quantum-well (QW) laser structure emitting at 1.3 mum have been experimentally determined as a function of current injection and temperature. The system is able to provide a maximum of 900 cm^-1 of material gain from the n = 1 transition despite an electron-hole overlap of 32%, however, the gain from the n = 2 transition becomes dominant before this value can be achieved. The presence of the n = 2 transition has a detrimental effect on device performance, limiting the usable gain from the first transition and increasing the total radiative recombination current. Energy level calculations show that reducing the hole QW to 4 nm would increase the separation of the n = 1 and n = 2 transition by a further 45 meV, reducing the limiting effect of the transition. Carrier distribution spectra show the carriers are in thermal equilibrium for the temperatures and injection currents studied. A low radiative efficiency for this structure is measured due to a very large nonradiative current. We believe a combination of different mechanisms contribute to the nonradiative current.     

我国近十年来激光与等离子体相互作用的研究

本文在回忆我国激光等离子体相互作用研究的基础上,简要地叙述了各个阶段的进展,同时提出了自己的看法。     

Spatial gain measurements in a chemical oxygen iodine laser (COIL)

The spatial distribution of small signal gain has been investigated on the RADICL device, a supersonic chemical oxygen-iodine laser (COIL). A frequency-stabilized, narrow linewidth diode laser system operating on the F=3→F=4 hyperfine levels of the (² P_1/2) to (²P_3/2) spin-orbit transition in atomic iodine was used as a small signal probe. A peak gain of 1.2%/cm was measured along the horizontal centerline of the single-slit, supersonic nozzle, which is about two times greater than measurements made on ReCOIL by Hager et al. (1988) and compares favorably with measurements made on the RotoCOIL device by Keating et al. (1990). Gain distribution was investigated under three I₂ flow conditions. Scans across the supersonic expansion indicate a gradient in gain distribution due to higher gas temperatures along the walls and mixing phenomena     

400 mm口径片状放大器JG2钕玻璃增益与激光输出性能实验研究

介绍了用于惯性约束聚变研究高功率激光驱动装置400 mm口径片状放大器系统的JG2钕玻璃片激光增益与激光输出性能等实验研究结果。利用一组三片长的400 mm口径4×2组合式片状放大器系统开展的增益性能实验结果表明,系统工作电压31 kV时小信号净增益系数达到5.37%/cm,小信号增益倍数为1.284倍/片/程,发次运行完成后利用0.3 m/s的洁净干燥气体进行冷却,热恢复时间约为2 h;利用大口径高通量验证实验平台开展的实验结果表明,基于JG2与N41钕玻璃片的优化组合使用最高输出能量达到21.3 kJ/1053 nm,目前已稳定运行500余发,未出现包边胶层异常与材料体损伤等故障。     

基质刻蚀的高功率外腔面发射激光器

为了降低光抽运外腔面发射激光器的热效应,提高激光器的输出功率,采用液体毛细键合方法将逆序生长的半导体外延片与高热导率的碳化硅散热窗口键合,并用化学刻蚀方法去除外延片的基质。实验研究了用基质刻蚀的外延片搭建的外腔面发射激光器的性能。当增益介质的有源区为InGaAs/AlGaAs多量子阱、抽运源为808nm的光纤耦合输出半导体激光器,输出镜对激光波长透过率为3%时,在室温下获得TEM00模的最大输出功率0.52W,激光波长1018nm,光谱线宽2nm(半峰全宽),激光器的光光转换效率约为20%。测得x方向与y方向的M2因子分别为1.01和1.00,说明输出光束为质量优良的近衍射极限高斯光束。结果表明,基质刻蚀技术可明显改善外腔面发射激光器的热性能,获得高功率、高光束质量的激光输出。     

Optically pumped intersublevel MidInfrared lasers based on InAs-GaAs quantum dots

We propose an optically pumped laser based on intersublevel transitions in InAs-GaAs pyramidal self-assembled quantum dots. A theoretical rate equations model of the laser is given in order to predict the dependence of the gain on pumping flux and temperature. The energy levels and wave functions were calculated using the 8-band k/spl middot/p method where the symmetry of the pyramid was exploited to reduce the computational complexity. Carrier dynamics in the laser were modeled by taking both electron-longitudinal optical phonon and electron-longitudinal acoustic phonon interactions into account. The proposed laser emits at 14.6 /spl mu/m with a gain of g/spl ap/ 570 cm/sup -1/ at the pumping flux /spl Phi/=10/sup 24/ cm/sup -2/ s/sup -1/ and a temperature of T=77 K. By varying the size of the investigated dots, laser emission in the spectral range 13-21 /spl mu/m is predicted. In comparison to optically pumped lasers based on quantum wells, an advantage of the proposed type of laser is a lower pumping flux, due to the longer carrier lifetime in quantum dots, and also that both surface and edge emission are possible. The appropriate waveguide and cavity designs are presented, and by comparing the calculated values of the gain with the estimated losses, lasing is predicted even at room temperature for all the quantum dots investigated.