基于准相位匹配产生近中红外波段的特性分析

基于周期极化晶体的Sellmeier方程和准相位匹配理论,对准相位匹配光参变振荡器的调谐特性进行了理论分析.通过数值模拟计算,得到了PPRTA晶体光参变振荡的调谐特性与极化反转光栅周期、晶体温度和抽运光波长等参量的关系曲线.并且与PPKTP晶体和PPLN晶体光参变振荡器的调谐特性进行了比较,研究了三者的不同之处,得出了PPRTA晶体的参量调谐特性优于PPKTP晶体和PPLN晶体的结论,与国外已报道的实验数据相吻合.证实了PPRTA晶体是一种可以产生可调谐近中红外光的理想准相位匹配非线性光学晶体.     

用周期极化KTP晶体高效倍频获得稳定461nm激光

实验采用准相位匹配的PPKTP晶体对922nm连续激光进行外腔谐振倍频,获得稳定461nm激光.实验装置采用一体化环形腔没计,实现最大耦合转换效率达73.3%,获得208 mW的461 nm蓝光输出.实验结论中通过分析,修正损耗误差,得到最佳耦合腔镜反射率,并深入讨论了耦合腔镜的两种反射率对倍频输出功率和效率的影响,同时就晶体吸收效应和热透镜效应对倍频试验的影响也进行了深入研究.     

利用PPKTP晶体倍频产生397.5nm激光的实验研究

使用周期性极化(PPKTP)晶体进行了795nm激光倍频的实验研究.实验中,基频(795nm)激光通过锥形放大器(TPA)实现了激光功率放大(400mW),再经过光纤整形后功率输出达100mW以上.将该激光单次通过PPKTP晶体,我们测量了倍频效率随晶体温度的变化关系.再将PPKTP晶体放入红外谐振倍频腔内,在最佳匹配温度和红外光共振条件下,获得了近14mW的397.5nm紫外光,倍频效率为13%.     

利用宽带倍频特性精确测量准相位匹配晶体的极化周期

 提出了利用准相位匹配晶体进行宽带脉冲倍频，再根据准相位匹配晶体的极化周期与倍频脉冲输出中心波长的相位匹配关系来精确测量准相位匹配晶体极化周期的新方法。理论分析了准相位匹配晶体的极化周期与倍频脉冲的光谱关系、倍频容许带宽与晶体长度的关系。研究表明：宽带脉冲倍频后输出的脉冲峰值波长对应于角度的调谐曲线具有对称性；对于长度为10 mm的极化晶体，其倍频容许带宽不到0.2 nm。实验中，采用了国产PPKTP晶体试验片，晶体尺寸为10 mm×7 mm×1 mm，理想极化周期9 300 nm。结果表明：对于中心波长为537.25 nm的倍频光，其对应的实际晶体极化周期为9 303.9 nm，大于晶体加工时的理想值；当倍频脉冲光谱测量精度为0.01 nm时，准相位匹配晶体的极化周期测量精度达到0.1 nm，远高于一般光学显微镜的观测精度。     

PPLN晶体差频中红外激光系统调谐特性研究

室温工作的连续可调谐相干光源在痕量气体检测技术中有着重要应用价值,光学非线性变换是获得室温运转中红外相干光源的有效途径,是对传统激光技术的有效补充.研究了基于准相位匹配原理的差频激光系统的温度和信号光波长调谐特性,从准相位匹配技术的一般位相匹配关系出发,推导了PPLN晶体差频准相位匹配的温度和信号光波长匹配带宽解析表达式;建立了基于PPLN晶体准相位匹配原理的宽调谐差频中红外激光系统,实现了3.2～3.7üm中红外相干光输出,最大输出功率约为1üW;对系统温度和信号光波长调谐特性进行实验研究,并与理论结果进行了比较和分析.     

理论构造周期极化KTiOPO_4晶体制备852和1550nm双色纠缠光

利用KTiOPO4(KTP)材料非线性系数d33对应的二阶非线性0-类准相位匹配,理论上设计构造了一种周期极化KTiOPO4晶体(PPKTP),当晶体温度为20℃时,晶体准相位匹配格子的周期为10.70μm。波长为550nm的激光泵浦由该晶体组成的光学参量振荡器能产生含852nm信号光和1550nm的闲置光的双色纠缠,其中信号光对应Cs原子吸收线,闲置光1550nm对应光纤通讯波长。该纠缠光对量子信息网络和原子信息存储有非常重要的意义。     

用于准相位匹配的LD泵浦Nd:YAG946nm连续激光光源

本文为泵浦质子交换准相位匹配波导器LiNbO₃提供了激光光源,用808nm半导体激光器泵浦Nd:YAG晶体,在室温下获得946nm激光连续输出大于120mW,斜率效率9.8%,并且在国内首次实现了LD泵浦Nd:YAG/KNbO₃473nm蓝色激光器的连续运转,报道了初步的实验结果并对此进行了详细的分析,提出了改进方案.     

用于准相位匹配的LD泵浦Nd∶YAG 946nm连续激光光源

本文为泵浦质子交换准相位匹配波导器 Li Nb O3 提供了激光光源 ,用 80 8nm半导体激光器泵浦 Nd∶ YAG晶体 ,在室温下获得 946 nm激光连续输出大于 1 2 0 m W,斜率效率9.8% ,并且在国内首次实现了 LD泵浦 Nd∶YAG/ KNb O3 4 73 nm蓝色激光器的连续运转 ,报道了初步的实验结果并对此进行了详细的分析 ,提出了改进方案 .     

光参量啁啾脉冲饱和放大的增益稳定性

 光参量啁啾脉冲放大（OPCPA）在饱和放大区存在一个增益稳定点，据此设计了一个输出稳定的三级OPCPA系统；第一、二、三级分别选用准相位匹配的周期极化钛氧磷酸钾（PPKTP）晶体、LBO晶体和KDP晶体作为增益介质。饱和放大时，增益随泵浦光强度变化时的增益输出稳定性明显改善，在泵浦光强度抖动低于6%的情况下，各级光参量放大器OPA输出的增益抖动小于1%。前级采用准相位匹配的PPKTP晶体作为增益介质，在远低于破坏阈值的30MW/cm²的泵浦功率密度下，可得到2×10⁵的饱和放大增益和20%的能量转换效率。     

基于PPKTP波导产生多通道光子对

提出了一种基于PPKTP波导利用自发参量产生多通道纠缠光子对的方案.计算在使用脉冲,连续激光,Ⅰ型、Ⅱ型相位匹配这些不同条件下,同时产生位于通信波段的多通道纠缠光子对的特性.结果显示该方案能够为量子密钥分配网络提供更为高效易行的方案.     

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为部分验证中国固态增殖剂TBM 模块中原尺寸模块结构设计的合理性和研制工艺的可行性,针对性地开展了TBM 小模块(仅高度为1/3)研制工作。在前期设计工作基础上,开展TBM 小模块结构详细优化设计与分析,提出模块加工、连接及集成装配等工艺方案,为TBM 小模块的工程化试制奠定坚实基础。     

中国固态增殖剂实验包层小模块工程结构设计与研制工艺探讨

为部分验证中国固态增殖剂TBM 模块中原尺寸模块结构设计的合理性和研制工艺的可行性,针对性地开展了TBM 小模块(仅高度为1/3)研制工作。在前期设计工作基础上,开展TBM 小模块结构详细优化设计与分析,提出模块加工、连接及集成装配等工艺方案,为TBM 小模块的工程化试制奠定坚实基础。     

Vertical-cavity surface-emitting laser fabricated by two implantations using tungsten wires as mask

The design and fabrication of a room-temperature continuous wave (cw) vertical-cavity surface-emitting laser is reported. The device was fabricated by two deep H⁺ implantations using parallel tungsten wires as the resist mask. The direction of the mask in the first implantation is perpendicular to that in the second. The fabrication process is the simplest ever reported for vertical-cavity surface-emitting laser fabrication. A lowest threshold current of 17 mA and a maximum light output power of 4 mW were obtained.     

Patterning of thin tin oxide film with nano-size particle for two-dimensional micro-gas sensor array

Thin tin oxide film with nano-size particle was prepared on silicon substrate by hydrothermal synthetic method and successive sol–gel spin coating method. The fabrication method of tin oxide film with ultrafine nano-size crystalline structure was tried to be applied to fabrication of micro-gas sensor array on silicon substrate. The tin oxide film on silicon substrate was well patterned by chemical etching upto 5 μm width and showed very uniform flatness. The tin oxide film preparation method and patterning method were successfully applied to newly proposed two-dimensional micro-sensor fabrication.     

Design and fabrication of bismith-silicate photonic crystal fiber

The process of design and fabrication of bismuth-silicate photonic crystal fiber (Bi-PCF) is reported. The Bi-PCF was fabricated by stack and draw method. This is the first trial of the fabrication of photonic crystal fiber made of bismuth-based glass with stack and draw method. The Bi-PCF structure was designed to reduce group-velocity-dispersion (GVD) in a plausible process. Thermal properties of the glass are investigated to establish the fabrication process. The applying pressure and pumping in fiber preform preparation were effectively utilized to control the air-hole diameter and arrangement. The fabricated Bi-PCF shows the well reduced GVD as the numerical calculation predicted. Fusion splicing between Bi-PCF and SMF-28 was also demonstrated.     

离焦写入线宽的动态高斯模型

为提高集成光学器件中的多线宽制作效率,提出了基于激光直接写入技术的离焦加工模式,即加工时激光束的聚焦点不落在胶层表面而是在其前方或后方;同时还建立了基于多个加工参量的线宽数学模型。此线宽模型首先假定激光束经物镜变换后,在像方任意离焦面上的能量仍保持高斯分布,其次还考虑了光束动态扫描引起的光斑线度对曝光能量分布的影响,故称其为动态高斯模型。此线宽模型涉及光功率、基片离焦量、光束扫描速度、胶层曝光能量阈值等加工参量。对线宽模型的验证在自行研发的极坐标型激光图形发生器上进行,实验表明:相对于不考虑光斑运动的静态高斯模型,动态高斯模型更为符合实验结果。     

Effects of natural antioxidants and high-energy fabrication methods on physical properties and oxidative stability of flaxseed oil-in-water nanoemulsions

The effects of high-energy fabrication methods, namely high-pressure homogenization (HPH) and ultrasonication (US), on physicochemical properties of flaxseed oil-in-water nanoemulsions (FNEs) containing clove essential oil (CEO) and/or pomegranate peel extract (PPE) were studied during storage at 4 and 25 °C. Nanoemulsions with relatively similar average droplet size were prepared by HPH and/or US. An increase in droplet size was observed over time. Lower storage temperature and fabrication by US increased Ostwald ripening rate. Higher storage temperature and fabrication by US decreased the centrifugal stability of nanoemulsions. CEO revealed better antioxidant properties than PPE. The oxidative stability was evaluated by determining secondary oxidation products, and fatty acids profile. The absence of antioxidant, fabrication by US, and higher storage temperature decreased the oxidative stability of nanoemulsions. The results of this study might be helpful in controlling the oxidation of FNEs during long-term storage and in designing functional foods and beverages.     

Improved silica fiber with enhanced ultraviolet transmission

When a silica optical fiber is used for transmitting ultraviolet (UV) light, the problems associated with the damage and transmission deterioration of silica fiber in the UV region need to be solved in the fabrication process. In this paper, an improved silica fiber fabrication process was presented to enhance UV transmission, which combined the UV pre-irradiation on high-OH concentration preform with heat treatment while drawing fiber. The impact of the structural defects and color centers was diminished greatly by the new method of fabrication. The experimental results accorded with the theoretical analysis,and transmission was improved about 0.4-0.7 dB/m for wavelength from 350 to 400 nm.     

Heterodyne receiver PICs as the first monolithically integrated tunable receivers for OFDM system applications

The state of the art in the fabrication of heterodyne receiver photonic integrated circuits (PICs) is described and in particular the results and experiences of the first fabrication of polarization-insensitive heterodyne receiver PICs are emphasized. The fabrication is based on a versatile integration concept with the potential also to fabricate other PIC architectures with different functionalities by only a single fabrication process.     

K9玻璃薄膜对离子交换磷酸盐玻璃波导表面保护的优化研究

采用镀K9玻璃薄膜方法来解决离子交换掺铒磷酸盐玻璃波导表面的侵蚀问题,对K9玻璃薄膜的厚度进行了优化研究。测量分析了样品的荧光光谱和荧光寿命,采用光学显微镜和棱镜耦合技术对不同K9玻璃薄膜厚度下制备波导的表面形貌和导光特性进行了表征和测试。结果表明,与掺铒磷酸盐玻璃原材料相比,镀K9玻璃薄膜后荧光光谱保持不变,荧光寿命稍有下降(约0.2 ms);K9玻璃薄膜的厚度在60~80 nm的范围内保护效果最佳。为下一步制备掺铒有源玻璃光波导器件奠定了良好的实验基础。