In:Mn:Fe:LiNbO3晶体光存储性能研究

在Mn:Fe:LiNbO3晶体中加入抗光折变元素铟,使用Czochralski法生长In:Mn:Fe:LiNbO3晶体,并对晶体进行氧化还原处理,测试了晶体紫外-可见吸收光谱.结果表明:铟的掺入使晶体吸收边发生移动,生长态晶体吸收边稍向紫移,氧化处理晶体吸收边紫移程度较大,还原处理晶体吸收边红移.通过二波耦合实验,使用输出功率30 mW的He-Ne激光器进行单光写入与擦除实验,测试了晶体记录过程中的响应时间与擦除时间.研究结果表明:In3 的掺入可通过提高擦除时间与响应时间之比,较大地提高晶体的动态范围;用生长态摩尔分数1%的In:Mn:Fe:LiNbO3晶体进行擦除时,衍射效率达到30%,衍射效率不随时间变化.     

氧化还原处理对Fe:LiNbO3晶体光折变性能及热固定效果的影响

在LiNbO3中掺进Fe2O3生长了Fe:LiNbO3晶体,并对晶体进行氧化、还原处理。利用二波耦合的方法,测试了不同还原处理的Fe:LiNbO3,晶体的指数增益系数、衍射效率及响应时间。测试了三种不同处理本热固定后的显影效率,记录了全息先栅的记录、热补偿及离子衰减过程。发现不同氧化还原处理的晶体在光折变性能和热固定效果上有不同的表现。     

Pr:Fe:LiNbO3晶体光折变性能的研究

在Fe∶LiNbO3中掺进Pr6011生长Pr∶Fe∶LiNbO3晶体。对晶体进行氧化－还原处理。测试晶体的指数增益系数、衍射效率、响应时间、光电导和信噪比。测试结果Pr∶Fe∶LiNbO3晶体的响应时间缩短,信噪比提高,克服了Fe∶LiNbO3响应时间长,光电导和信噪低的缺点。以Pr∶Fe∶LiNbO3晶体作为存储元件实现了全息关联存储。     

Ce:Eu:LiNbO3晶体制备及光折变性能

为了昨到光折变性能优良的晶体材料，在LiNbO3中掺进CeO2和Eu2O3，生长Ce:LiNbO3和Ce:Eu:LiNbO3单晶体，对晶体进行极化和氧化还原处理，并利用XRD、UV-VIS及二波耦合光路测试了晶体的晶格常数、吸收光谱、指数增益系数和响应时间。结果表明，Ce:Eu:LiNbO3晶体的晶格常数比Ce:LiNbO3晶体小，其吸收边比CeLiNbO3晶体红移更多，指数增益系数比Ce:LiNbO3晶体大，而响应时间比Ce:LiNbO3晶体的要短，Ce:Eu:LiNbO3是优良的光折变晶体材料。     

双掺铈锰铌酸钾锂晶体的生长及光折变性能的研究

在铌酸钾锂(KLN)中掺进CeO2和MnCO3,采用Czchralski法首次生长CeMnKLN晶体,测试晶体的晶格常数,CeMnKLN晶体的晶格常数变小.测试晶体的吸收光谱,它的吸收边相对KLN晶体发生红移.研究晶体吸收边发生红移的原因.以二波耦合光路测试CeMnKLN晶体的指数增益系数Γ.它的指数增益系数最大值Γmax=9.2cm-1,大于KLN晶体的Γ值.     

高掺镁LiNbO3晶体抗光折变性能研究

在LiNbO3中掺进MgO以提拉法生长Mg(1mol%)LN,Mg(3mol%)LN,Mg(5mol%)LN,Mg(7mol%)LN,和Mg(9mol%)LN晶体.改进晶体生长工艺条件,解决了在生长中出现的脱溶,散射颗粒,生长条纹等缺陷.生长出高质量高掺镁LiNbO3晶体.测试MgLiNbO3晶体的红外光谱,当Mg2+的浓度达到或超过阈值浓度的MgLiNbO3晶体,OH-吸收峰移到3535cm-1,晶体抗光损伤能力比LiNbO3晶体提高两个数量级以上.测试MgLiNbO3晶体的倍频性能(相位匹配温度,倍频转换效率)MgLiNbO3晶体的相位匹配温度随Mg2+浓度的增加而改变,Mg(5mol%)LN,晶体的相位匹配温度达到116℃,Mg(9mol%)LN晶体在室温附近.     

掺铟LiNbO3晶体抗光折变效应增强机理的研究

在LiNbO3中掺进不同浓度的抗光折变杂质离子In3+,生长In(2mol%)LiNbO3和In(3mol%)LiNbO3晶体.研究InLiNbO3晶体的结构和In3+离子在LiNbO3晶体中的占位,利用光斑变形法和全息法测试了InLiNbO3晶体的抗光折变性能,分析了In3+使LiNbO3晶体抗光折变效应增强的机理.     

掺镁近化学计量比LiNbO3晶体的生长

利用提拉法，从掺入11mol％K2O和1mol％MgO的化学配比LiNbO3熔体中生长了高质量的掺镁近化学计量比LiNbO3晶体．与同成分LiNbO3晶体相比，紫外吸收边发生明显蓝移，OH^-红外吸收峰的位置和波形也发生了显著的变化，初步断定晶体中Mg^2 的掺杂浓度已达到抗光伤阈值浓度．酸腐蚀结果表明，晶体具有区域性单畴结构。     

掺铟LiNbO3晶体抗光折变效应增强机理的研究

在LiNbO3中掺进不同浓度的抗光折光折变杂质离子In^3 ,生长In(2mol％）：LiNbO3和In(3mol％）：LiNbO3晶体。研究In:LiNbO3晶体的结构和In^3 离子在LiNbO3晶体中的占位,利用光斑变形法和全息法测试了In:LiNbO3晶体的抗光折变性能,分析了In^3 使LiNbO3晶体抗光折变效应增强的机理。     

近化学计量比In:Fe:LiNbO3晶体光学性能的研究

采用助溶剂法以TSSG技术生长近化学计量比SInFeLiNbO3晶体.测试S InFeLiNbO3晶体的晶格常数,SInFeLiNbO3晶体的晶格常数既小于LiNbO3晶体也小于InFeLiNbO3晶体.晶格常数的变化是由于Li+取代反位铌NbLi4+和占据锂空位引起的.测试SInFeLiNbO3晶体的红外光谱,OH-吸收峰移到3503.cm-1,测试SInFeLiNbO3晶体的指数增益系数Γ,SInFeLiNbO3晶体的Γ值达到28cm-1,高于InFeLiNbO3晶体.     

Phase Formation During Nonisothermal Decomposition of the Freeze-Dried Bi:Pb:Sr:Ba:Ca:Cu = 1.8:0.4:1.8:0.2:1.2:2.0 Complex Nitrate Powder

Nitrate powder with cation composition Bi:Pb:Sr:Ba:Ca:Cu = 1.8:0.4:1.8:0.2:1.2:2.0 was obtained by spray-frozen, freeze-drying technique. Samples of the nitrate precursor powder were placed in a heated furnace (heating rate 100°C/min) and extracted in air when temperature of the powdered samples attained values of 439, 495, 550, 600, 640, 647, 717, 766, 814, and 850°C. Samples have been investigated by X-ray diffraction analysis. The obtained data allow us to propose and discuss phase formation and decomposition processes and reactions that occur in non-isothermal conditions at different temperatures during thermal decomposition of the nitrate powder.     

Flash-lamp-pumped Ho:Tm:Cr:YAG and Ho:Tm:Er:YLF lasers: modeling of a single, long pulse length comparison

Two methods of producing the long pulse lengths that promote efficient extraction of energy from low-gain, quasi-four-level lasers are analyzed. A long pulse length output can mitigate laser-induced damage effects and can be generated in quasi-four-level lasers by two disparate methods. One method utilizes Q-switching techniques in resonators designed to extend the pulse length and another utilizes the first pulse in a relaxation oscillation pulse train. Models for quasi-four-level lasers are derived here taking into account the nonnegligible thermal population of the lower laser level. Closed-form expressions are derived for both modes of operation of quasi-four-level laser systems so the parametric dependencies of both forms of operation become obvious, allowing facile comparison. In addition, a combined absorption and quantum efficiency, germane for flash-lamp pumping, is calculated for both Cr and Er sensitizers. Although the former has the advantage of broad absorption bands, the latter has the advantage of a quantum efficiency approaching 3.     

Flash-lamp-pumped Ho:Tm:Cr:YAG and Ho:Tm:Er:YLF lasers: experimental results of a single, long pulse length comparison

Flash-lamp-pumped, room-temperature Ho:Tm:Cr:YAG and Ho:Tm:Er:YLF are compared for single but long pulse operation, with pulse lengths of approximately 1.0 mus. Under similar operating conditions in normal-mode operation, a slope efficiency of 0.0331 was observed for Ho:Tm:Er:YLF compared with 0.0047 for Ho:Tm:Cr:YAG. For Q-switched operation, Ho:Tm:Er:YLF yielded a slope efficiency of 0.0075. In comparison, a slope efficiency of 0.0012 was obtained for Ho:Tm:Cr:YAG. Two methods of producing long pulse lengths are compared: pulse selection of normal-mode relaxation oscillations and Q-switching in a long resonator. Theoretical models developed in a companion paper for normal-mode relaxation oscillations and Q-switching in quasi-four-level solid-state lasers are in agreement with the experimental results.     

Electroluminescence of (Zn:Cd)S:Mn:Sm:Cl phosphors

The effect of field strength and frequency on electroluminescence brightness has been investigated for the binary systems (Zn:Cd)S:Mn:Cl and (Zn:Cd)S:Mn:Sm:Cl. The voltage dependence of the time averaged electroluminescent brightness shows the relation B = B_o exp ($\text{?}\text{C}\text{√}\text{v}$ and holds good over a wide range of frequencies, thus indicating that the mechanism of excitation is acceleration collision. The dependence of constants B_o and C on frequency of the applied field shows that the brightness of the electroluminescence is found to saturate at higher frequencies. It has been observed that EL peak emissions for these phosphors were found to be at 560 nm and 580 nm.     

Optical and EPR spectroscopy of Zn:Cr:ZnSe and Zn:Fe:ZnSe crystals

Optical and EPR characterization of Cr and Fe doped ZnSe crystals annealed in Zn vapor revealed a strong bleaching of the divalent state of transition metal ions. Photo induced EPR kinetics were studied in 20–80 K temperature range. Analysis of time-dependent data reveals Cr¹⁺ signal rise time decreases with increasing temperature. The non-exponential decay of Cr¹⁺ concentration were analyzed using Auger-type recombination process. The photoluminescence quantum yield of Cr²⁺ ions at ⁵E(D) → ⁵T₂(D) mid-IR transition excited via chromium ionization process was measured to be close to 100%.     

Growth of YLF:Yb:Tm:Nd for optical applications

The focus of this study is the behavior of Tm, Yb and Nd ions in the LiYF₄ (YLF) crystal. One YLF crystal was successfully grown by the Czochralski method; it was doped with 20 mol% Yb, 1.3 mol% Nd and 0.05 mol% Tm. The segregation coefficients of the dopants and lattice parameters were determined. The spectroscopic properties of samples with different amounts of Nd were obtained from absorption and emission studies.