双掺杂LiNbO_3晶体光谱和光折变特性

报道了双掺杂Ce :Fe ,Ce :Mn ,Mn :Fe生长态LiNbO3(LN)的光谱及光折变效应二波耦合增益特性 .研究表明 ,双掺杂浓度较高时 ,生长态的LiNbO3晶体的透过率光谱范围较小 ,光折变效应二波耦合增益较低 .几种双掺杂晶体都比单掺Fe晶体的光折变效应二波耦合增益低 ,表现出较强的抗光折变特性     

双掺杂LiNbO3晶体光谱和光折变特性

报道了双掺杂CeFe,CeMn,MnFe生长态LiNbO3(LN)的光谱及光折变效应二波耦合增益特性.研究表明,双掺杂浓度较高时,生长态的LiNbO3晶体的透过率光谱范围较小,光折变效应二波耦合增益较低.几种双掺杂晶体都比单掺Fe晶体的光折变效应二波耦合增益低,表现出较强的抗光折变特性.     

掺Mn钾钠铌酸锶钡晶体光折变研究

实验中，生长、极化、制备出了掺０．０２％和０．０４％Ｍｎ钾钠铌酸锶钡晶体样品，并对其二波耦合、二波耦合响应时间及自泵浦相位共轭进行了测量．研究发现：掺Ｍｎ可以有效地增加钾钠铌酸锶钡晶体的吸收，在波长６３２．８ｎｍ，０．０２％Ｍｎ晶体样品的二波耦合增益系数大于７ｃｍ－１而０．０４％Ｍｎ晶体样品的二波耦合增益系数大于９ｃｍ－１，０．０４％Ｍｎ晶体样品二波耦合增益时间响应比０．０２％Ｍｎ晶体样品二波耦合增益时间响应快近４倍；０．０４％Ｍｎ晶体样品有很高自泵浦相位共轭反射率，高达７０％．实验研究表明：掺Ｍｎ可以提高钾钠铌酸锶钡晶体在长光波段的光折变性能     

氧化还原对掺铁LiNbO3晶体的吸收边和透过率的影响

着重研究了经过不同氧化还原处理的不同掺杂及浓度的掺铁铌酸锂晶体的吸收边和透射谱，认为晶体的能带结构随掺杂离子及离子的价态变化而变化，并解释了吸收边的有关实验结果．     

温度对KNSBN晶体二波耦合增益的影响

对３００Ｋ至４２０Ｋ温度范围内的光折变晶体ＫＮＳＢＮ（钾钠铌酸锶钡）的前向二波耦合特性进行了实验观测和理论分析，结果表明，光增益不仅取决于实验的几何配置而且对温度有较大的依赖性，由室温度提高至３６０Ｋ可提高放大倍数一倍以上。     

温度对KNSBN晶体二波耦合增益的影响

对３００Ｋ至４２０Ｋ温度范围内的光折变晶体ＫＮＳＢＮ（钾钠铌酸锶钡）的前向二波耦合特性进行了实验观测和理论分析,结果表明,光增益不仅取决于实验的几何配置而且对温度有较大的依赖性,由室温提高温度至３６０Ｋ可提高放大倍数一倍以上     

用铁电晶体四波混频的实时光学检测

对利用铁电晶体掺铁铌酸锂(LiNbO_3:Fe)作记录介质的简并四波混频干涉计量术进行了讨论,提出一种实时测量透明物体的折射率及面形分布不均匀性的实验原理及方法,分析了掺铁铌酸锂晶体在测量中的记录特性,并给出了测量平板玻璃样品的试验结果。     

质子交换在铌酸锂和同化学剂量比铌酸锂晶体中形成光波导

报道了用质子交换法在铌酸锂晶体和同化学剂量比铌酸锂晶体中形成了光波导,在633和1539nm波长下,用棱镜耦合法测量了波导的暗模特性;端面耦合得到波导的近场光强分布,与普通铌酸锂质子交换形成光波导的近场输出相比,输出光强均匀而且比较亮,说明在同化学剂量比的铌酸锂中形成的光波导质量要好些．对普通铌酸锂晶体质子交换光波导,研究了波导退火特性,经过退火,折射率分布由阶跃型转变成渐变型的,退火的时间越长,折射率分布变化的趋势越缓慢;并给出了不同交换时间下样品的RBS／Channeling谱,与未进行交换的样品相比,质子交换铌酸锂的沟道谱的产额有增高,而且交换时间的越长,产额增高的越多．     

近化学计量比Fe:LiTaO3晶体的光折变性能

采用顶部籽晶溶液法（TSSG）,生长直径约10-15mm,长度为10mm的近化学计量比掺铁铌酸锂（Fe：SLN）和近化学计量比掺铁钽酸锂（Fe：SLT）晶体．采用二波耦合全息法测量了晶体的记录时间,擦除时间和饱和衍射效率;采用光斑畸变法测量了抗光损伤阈值．与Fe：SLN晶体相比,Fe：SLT晶体的饱和衍射效率降低,记录时间减小,抗光损伤能力显著提高,Fe：SLT晶体的抗光损伤闽值为420MW／cm^2。     

Ce，Sm联合掺杂TiO2薄膜制备及其电致变色特性

以钛酸四丁酯、硝酸铈和硝酸钐为主要原料,采用溶胶-凝胶法在ITO导电玻璃基片表面制备Ce,Sm联合掺杂TiO2电致变色薄膜,Ce,Sm掺杂的摩尔分数分别为0,2%,5%和10%.采用电化学工作站和紫外可见分光光度计,研究了薄膜的循环伏安特性和光谱特性.结果表明,Ce,Sm的摩尔分数为2%时,薄膜的峰值电流最大,电荷存储能力最强,注入电荷密度为1512mC·cm-2,循环可逆性K值为07.Ce,Sm的摩尔分数为5%和10%时,随着掺杂量的增加,薄膜的峰值电流减小,电荷存储能力变弱.Ce,Sm掺杂TiO2薄膜在可见光范围内具有更好的光学透明度,着色时颜色很浅,着色态和褪色态的光谱透过率几乎一致,均在90%以上,可以在电致变色玻璃中作为离子存储材料.     

The Effect of Oxidation／Reduction Disposing on Optical Properties of Mg： Fe： Mn： LiNbO3 Crystals

The congruent tri-doped Mg: Mn: Fe: LiNbO3 crystal has been grown by Czochralski method. Some crystal samples are reduced in Li2CO3 powder at 500℃ for 24 hours or oxidized for 10 hours at 1100 ℃ in Nb2O5 powder. Compared with As-grown Mg:Mn:Fe:LiNbO3, the absorption edge in UV-Vis. absorption spectrum of the oxidized sample and the reduced shifts to the violet and the red, respectively. Reduction increases the absorption of crystals in visible light region. In two-wave coupling experiments, the writing time, maximum diffraction efficiency and the erasure time of crystal samples in the same conditions are determined. The results indicate that oxidation and reduction disposing has great effect on the holographic recording properties of these crystals. The reduced crystal exhibits the fastest response time of 160 s anmng the crystal series. The mechanism of post-disposing effect on the holographic recording properties of Mg:Mn:Fe:LiNbO3 crystals are investigated.     

光折变晶体中与光强有关的二波耦合及能量转移

用一种模型对对称入射的两束相干光在光折变晶体内的耦合即能量转移进行了分析,导出了单边入射二波耦合的信号光放大率的解析表达式。分析了对KNSBN光折变晶体的二波耦合测量结果,求得与光强有关的耦合常数值。此外,给出了信号光放大率及两束光的光强随入射光强、束比、吸收系数、饱和耦合常数及介质厚度变化的曲线。     

Optical Property of LiNbO3 Crystal Codoped with In, Mg and Fe

In2O3, MgO and Fe2O3 were doped in LiNbO3 and Czochralski method was used to grow In:Mg:Fe:LiNbO3 crystals. The OH- extension transmission spectra, light scattering resistance ability, two wave coupled diffraction efficiency and response time of the crystal were measured. Codoping In and Mg in crystal will improve its light scattering resistance ability and response time. Doping In can increase the ability to replace antisite Nb and decrease the doping quantity of Mg. All these are propitious to improve the optical homogeneity of crystal. Doping Fe can improve the photorefractive sensitivity for LiNbO3 crystal. We discussed the site of In, Mg and Fe in LiNbO3 crystals and the influence of the absorption peak of OH- transmission spectra on photorefractive property for LiNbO3 crystal.     

Optical Property of LiNbO3 Crystal Codoped with In, Mg and Fe

In2O3, MgO and Fe2O3 were doped in LiNbO3 and Czochralski method was used to grow In:Mg:Fe:LiNbO3 crystals. The OH- extension transmission spectra, light scattering resistance ability, two wave coupled diffraction efficiency and response time of the crystal were measured. Codoping In and Mg in crystal will improve its light scattering resistance ability and response time. Doping In can increase the ability to replace antisite Nb and decrease the doping quantity of Mg. All these are propitious to improve the optical homogeneity of crystal. Doping Fe can improve the photorefractive sensitivity for LiNbO3 crystal. We discussed the site of In, Mg and Fe in LiNbO3 crystals and the influence of the absorption peak of OH- transmission spectra on photorefractive property for LiNbO3 crystal.     

吸收及界面内反射对逆向二波混合的影响

以Shooting法为基础,研究了吸收、增益和晶体厚度对光折变晶体中逆向二波混合的影响,对近似计算所引起的误差进行了讨论。对晶体表面内反射对光束透过率的影响,提出了以Shooting法为基础的自洽计算方法,计算了透过率与晶体表面反射率的关系。     

Near-infrared sensitivity enhancement of photorefractive polymer composites by pre-illumination

Among the various applications for reversible holographic storage media, a particularly interesting one is time-gated holographic imaging (TGHI). This technique could provide a noninvasive medical diagnosis tool, related to optical coherence tomography. In this technique, biological samples are illuminated within their transparency window with near-infrared light, and information about subsurface features is obtained by a detection method that distinguishes between reflected photons originating from a certain depth and those scattered from various depths. Such an application requires reversible holographic storage media with very high sensitivity in the near-infrared. Photorefractive materials, in particular certain amorphous organic systems, are in principle promising candidate media, but their sensitivity has so far been too low, mainly owing to their long response times in the near-infrared. Here we introduce an organic photorefractive material -- a composite based on the poly(arylene vinylene) copolymer TPD-PPV -- that exhibits favourable near-infrared characteristics. We show that pre-illumination of this material at a shorter wavelength before holographic recording improves the response time by a factor of 40. This process was found to be reversible. We demonstrate multiple holographic recording with this technique at video rate under practical conditions.     

Ce：KNSBN晶体光折变效应温度特性实验研究

介绍了Ce:KNSBN光折变晶体温度效应（300—400K）的实验研究,分别给出了两波耦合和四波混频相位共轭的测量结果。     

An updatable holographic three-dimensional display

Holographic three-dimensional (3D) displays provide realistic images without the need for special eyewear, making them valuable tools for applications that require situational awareness, such as medical, industrial and military imaging. Currently commercially available holographic 3D displays use photopolymers that lack image-updating capability, resulting in restricted use and high cost. Photorefractive polymers are dynamic holographic recording materials that allow updating of images and have a wide range of applications, including optical correlation, imaging through scattering media and optical communication. To be suitable for 3D displays, photorefractive polymers need to have nearly 100% diffraction efficiency, fast writing time, hours of image persistence, rapid erasure, and large area-a combination of properties that has not been shown before. Here, we report an updatable holographic 3D display based on photorefractive polymers with such properties, capable of recording and displaying new images every few minutes. This is the largest photorefractive 3D display to date (4 x 4 inches in size); it can be recorded within a few minutes, viewed for several hours without the need for refreshing, and can be completely erased and updated with new images when desired.     

硅酸铋晶体四波混频共轭反射率分析

从Ｋｕｋｈｔａｒｅｖ能带传递模型出发，导出了光折变四波混频共轭反射率对晶体内光栅空间频率的响应及空间电荷场的关系，给出了硅酸铋晶体内允生载流子两种输运机制对共轭反射率频率响应的影响的理论解释。实验结果与理论分析相吻合。