Pulsed-pumped optical fiber amplifier

With the use of pulsed pumping, an optical fiber amplifier with all-fiber structure is developed based on the fused tapered fiber combiner and Yb^3＋-doped double cladding fiber （YDCF）. From the experimental results, 47-dBm peak power and 100-ns pulse duration are obtained when the repetition rate of pumping pulses is 100 Hz. The gain of the amplifier is up to 30 dB. It is shown that due to the use of pulsed pumping, pump light emits only when the signal light reaches the amplifier and thus the amplified spontaneous emission （ASE） is significantly suppressed.     

车载综合观瞄系统的设计与实现

现代战争要求战场目标搜索设备能够在机动条件下实现快速自动搜索、发现、识别远距离目标,并对敌方目标进行威胁排序,将目标的坐标进行精确定位后把目标信息传递给后方.提出了一种新型综合的特种车辆观瞄系统,对其5个组成部分?全景组件、可见光连续变焦组件、高性能红外热像仪组件、智能控制组件、云台光机组件进行研究与设计,并对系统的组...     

亚微米光栅周期的软X射线多层膜光栅的衍射效率研究

简要叙述软x射线多层膜位相光栅的理论设计、实验制备,详细给出了在北京同步辐射装置3B1束线上对多层膜位相光栅衍射效率的测试,以及对测试结果的分析,并与理论值进行了比较. 关键词：     

便携式激光诱导击穿光谱最新研究进展

作为一种新型快速的物质成分分析技术,激光诱导击穿光谱(Laser-Induced Breakdown Spectroscopy,LIBS)已经在越来越多的工业领域中被证明具有巨大的应用潜力.然而,由于野外作业或工业现场检测环境嘈杂恶劣,对仪器设备的尺寸和抗恶劣环境的能力提出了更高的要求.近年来,新型激光器的发展进一步促...     

硅酸铅玻璃光敏性研究

采用四倍频的Nd∶YAG脉冲激光 (波长 2 6 6nm ,脉宽 10ns)对氧化铅摩尔分数在 0 3至 0 5的硅酸铅玻璃体样品进行照射 ,并对照射前后样品的折射率及紫外可见吸收光谱进行了测量。研究发现不同能量密度的2 6 6nm激光照射硅酸铅玻璃体样品 ,会使样品的紫外可见吸收光谱产生不同的变化 :当 2 6 6nm激光能量密度较高时 (15 0mJ/cm2 ) ,样品在可见区域的吸收系数明显增大 ,样品表面会产生褐色斑点 ;而当 2 6 6nm激光能量密度较低时 (5 0mJ/cm2 ) ,尽管累计剂量较大 ,样品表面无斑点产生 ,吸收系数稍有增加 ,而折射率下降明显 ,最大Δn =- 0 .2 5± 0 .0 4。对氧化铅摩尔分数为 0 4 3的硅酸铅玻璃用不同能量密度的 2 6 6nm激光进行照射 ,发现当激光能量密度大于某一阈值时 ,样品在可见区域的吸收系数突然增大 ,这可能是由于硅酸铅玻璃吸收 2 6 6nm激光能量导致局部温度升高而引起玻璃结构改变所致。     

磷酸催化合成2,4-二叔丁基苯酚的研究

研究了以磷酸为催化剂,苯酚和叔丁醇为原料合成2,4-二叔丁基苯酚。合成产物经过利用受阻酚的性质分离提纯,得到高纯度的2,4-二叔丁基苯酚,并考察了影响反应的因素。结果表明:酚醇摩尔比为1∶3,催化剂85%磷酸的用量为10m L,反应时间为5h,反应温度为60℃是最适宜的反应条件;产物收率达57.1%。     

Photosensitivity and photoluminescence of Sn/Yb codoped silica optical fiber preform

Sn/Yb codoped silica optical fiber preform is prepared by the modified chemical vapor deposition （MCVD） followed by the solution-doping method. Ultraviolet （UV） optical absorption, photoluminescence （PL） spectra under 978-nm laser diode （LD） pumping, and refractive index change after exposure to 266-nm laser pulses are obtained. There is only a little change in the PL spectra while a positive refractive index change up to 2×10^-4 is observed after 30-min exposure to 266-nm laser pulses. The results show that both of the peculiar photosensitivity of Smdoped silica and the gain property of Yb-doped silica fiber are preserved in the Sn/Yb codoped silica optical fiber preform. The experimental data suggest that the photosensitivity of the fiber preform under high energy density laser irradiation should be mainly due to the bond-breaking of oxygen deficient defects, while under relatively low energy density laser irradiation, the refractive index change probably originates from the photoconversion of optically active defects.     

基于神经网络的反射式表面粗糙度光纤传感器

本文提出了一种新型表面粗糙度光纤传感器,阐述了它的结构、工作原理,给出了测 试结果。利用神经网络很强的输入-输出映射能力,将实验数据交给神经网络处理,减小了测量误差,提高了测量精度,扩大了测量范围。本系统能准确地识别Ra分别为0.012μm, 0.025μm,0.5μm,0.1μm的被测表面。     

Double-pass ytterbium-doped fiber amplifier with high gain coefficient and low noise figure

We have proposed and demonstrated a double-pass ytterbium-doped fiber amplifier using an optical circulator and a fiber Bragg grating as reflector. When the signal has passed through the ytterbium-doped fiber once, it reflects off a 0.2-nm passive fiber Bragg grating filter. This reduces amplified spontaneous emission (ASE) noise from the first pass. The input signal light is amplified both forward and backward through ytterbium-doped fiber. With this double-pass configuration, 1053.15-nm unsaturated signal gain of 28 dB, gain coefficient of 1.1 dB/mW, and noise figure of less than 4 dB are achieved at 977-nm pump power of 68 mW. It is also found that this double-pass configure provides enhancing gain coefficient and improving noise figure by comparison with single-pass configuration.