光纤布拉格光栅电流传感的理论和实验研究

对皮磁致伸缩棒调谐光纤布拉格光栅为基础的新型电流传感器进行了理论和实验研究。将一个光纤布拉格光栅牢固地粘贴在一置于多层螺线管中心部分的磁致伸缩棒上，构成传感头。当通过螺线管的电流改变时，磁致伸缩材料在均匀磁场的作用下产生沿纵向的应变并传递到光纤光栅上，从而导致光纤光栅的布拉格波长移动。外加电流和波长移动之间的关系是线性的，线性调谐的波长范围为0.9nm，电流强度范围为900mA，灵敏度约为1000mA/nm，电流强度可精确到10mA。理论和实验符合得很好。     

宽带可调谐掺Yb3+双包层光纤激光器的研究

利用闪耀光栅构成可调谐Littrow外腔,对掺Yb³⁺双包层光纤激光器的波长调谐输出进行了实验研究.激光调谐输出波长范围70nm.针对光纤内的双折射效应对激光的输出功率的影响,实验中使用了在线光纤偏振控制器,从而有效地减小了调谐曲线的起伏及其与荧光谱的差别,并得到了窄线宽、线偏振、宽带调谐的激光输出.     

光纤布喇格光栅的金属管封装与电调谐

本文用薄金属套管对光纤光栅进行了封装,并利用其进行了光纤布喇格光栅的电调谐实验.这种调谐方法保持了光纤光栅体积小的优点,操作简便,可远距离实现,光纤光栅的波长变化与电流的平方或电功率成正比.实验中用3.2A的电流获得了3nm的波长调谐,调谐速率约为0.59nm/W.     

π相移光纤光栅的温度调谐特性

根据π相移光纤光栅的温度可调谐原理,使用半导体制冷器(TEC)和制冷片控制π相移光纤光栅的温度,从而改变其中心波长。随着温度升高,π相移光纤光栅的中心波长向长波方向线性漂移,温度从0℃变化到95℃时,中心波长从1548.921nm变化到1550.664nm,波长改变量为1.743nm,灵敏度约为18.35pm/℃。为了验证π相移光纤光栅温度调谐的特性,采用与其匹配的高反光纤光栅构成了C波段环形腔光纤激光振荡器,利用π相移光栅的窄带滤波特性实现了窄线宽激光输出,并通过控制π相移光栅的温度实现了输出激光波长的连续调谐。     

掺Yb双包层光纤激光器波长调谐输出

采用调节腔损耗以调节阈值的方法实现了掺Yb双包层石英光纤激光器的波长调谐输出 调谐范围达50nm 、步长约2nm 当损耗增大阈值升高时,激射波长向短波方向漂移.利用石英中Yb³⁺的能级结构和光谱特性对以上规律进行了定性解释.     

785nm便携式光栅外腔可调谐半导体激光器的研制和输出特性

针对移频激发拉曼光谱测试系统的小型化需求,在Littrow结构中,采用商用的785nm大功率激光二极管作为增益器件,构建了一款便携式光栅外腔可调谐半导体激光器。该激光器通过采用一种新型的波长调谐方法,即以改变半导体增益器件相对于准直透镜的水平位置来实现波长的连续调谐,实现了尺寸为140mm×65mm×50mm的小型化结构设计。相比于传统的旋转衍射光栅改变光线在光栅上的入射角来实现波长调谐的方式,该方法有效地缩减了增益器件的平移距离,从而有利于便携式外腔激光器波长的快速宽带调谐。实验结果表明,该激光器具有较宽的波长调谐范围,在340~900mA注入电流下均可实现10nm以上的波长调谐,尤其在900mA大注入电流下,其波长调谐覆盖779.40~791.07nm,调谐范围可达11.67nm,且激射线宽小于0.2nm,单波长输出功率最高可达280mW,放大的自发辐射抑制比大于25dB,呈现出较优异的输出性能,满足移频激发拉曼光谱检测系统对光源的基本要求。此外,该激光器可采用一微型压电陶瓷驱动器来实现波长的电动调谐,实验获得了1.35nm的波长调谐范围,证实了所制785nm便携式光栅外腔可调谐半导体激光器适合作为便携式移频激发拉曼光谱检测系统的光源用于减除原始拉曼光谱中的荧光背景。     

基于飞秒激光直写光纤光栅的掺镱光纤激光器

 利用飞秒激光微加工技术,可以在光纤纤芯内直写出布拉格光栅,它与传统的光纤光栅制作方法相比,具有耗时短、无需光敏光纤、周期可任意设定、光栅稳定性高等优点。采用800 nm钛宝石飞秒激光器,在Hi1060光纤内写入一支8 mm长的布拉格光栅,光纤光栅的周期为2.9 μm,这是中心波长为1 042 nm的八阶光纤布拉格光栅。将所得光栅与一段有源的双包层光纤熔接,作为激光输出镜,利用975 nm的LD光纤模块作为泵浦源,采用端泵浦技术构成双包层光纤激光器。双包层光纤采用Nufern公司镱(Yb³⁺)离子掺杂双包层光纤,光纤长度3 m。所得激光器的输出功率为71.1 W,中心波长1 042 nm,带宽约为0.8 nm。     

金原子团簇的分频散射光谱研究

液相金原子团簇是一种非线性光学介质.它在580nm处产生一个最强共振散射峰.当激发波长为290nm(1.03×10¹⁵Hz)时,液相金原子团簇在580nm(1/2×1.03×10¹⁵Hz)和870nm(1/3×1.03×10¹⁵Hz)分别产生一个1/2分频和1/3分频散射峰;当激发波长为580nm(5.02×10¹⁴Hz)时在290nm(2×5.02×10^-14Hz)和870nm(2/3×5.02×10¹⁴Hz)分别产生一个2倍频和2/3分频散射峰;当激发波长为870nm(3.34×10¹⁴Hz)时在580nm(3/2×3.34×10¹⁴Hz)和290nm(3×3.34×10¹⁴Hz)分别产生一个3/2分频和3倍频散射峰.分频散射和倍频散射峰与共振散射峰具有相似的散射行为.从激励光与液相金原子团簇相互作用的运动方程出发,根据傅氏变换理论,较好地解释了液相金原子团簇产生的一些非线性散射光谱.     

高功率全正色散锁模掺Yb3+双包层光纤飞秒激光器

以芯径为30 μm的掺Yb³⁺双包层光纤为增益介质, 利用非线性偏振旋转技术以及光栅-小孔结构组成的光谱滤波器提供有效的振幅调制, 实现了稳定的全正色散耗散孤子锁模运转. 激光器直接输出重复频率为76.6 MHz、平均功率达6.3 W的超短脉冲, 单脉冲能量可达82 nJ. 直接输出脉冲宽度为1.33 ps, 经腔外压缩后的宽度为377 fs. 通过调节光栅角度还实现了输出脉冲中心波长在1025—1078 nm范围内的调谐.     

不同波长激光辐照对痢疾杆菌生物学效应的影响

分别采用功率密度为1.7W/cm²、照射剂量为2000J/cm²的Ar⁺激光与LD激光辐照高耐药性的志贺氏福氏痢疾杆菌,波长较短的Ar⁺激光(488nm)所引起细菌的致死率与药敏实变率明显高于波长较长的LD激光(808nm),即波长较短的Ar⁺激光的辐照导致细菌耐药性显著降低.     

A Miniaturized Tunable Filter Based on a Fiber Bragg Grating Loaded by a Ceramic-Tube Microheater

A miniaturized 1.55 μm tunable fiber Bragg grating (FGB) filter is proposed and successfully demonstrated using an aluminum ceramic-tube with a tungsten thick film sleeve microheater. Fine tuning of the Bragg reflective wavelength with 0.0135 nm/^oC is achieved by adding the constant thermal distribution along the uniform FBG with a 0.3 nm bandwidth. Furthermore, a 1.5 nm linearly chirped reflection bandwidth is obtained by thermal gradient loading.     

基于激光器激射特性的新型应变传感系统

报道了一种基于掺铒光纤激光器瞬态特性的新型应变传感系统.用光纤环反射镜和光纤Bragg光栅(FBG)构成Fabry-Perot线型腔.腔内插入一个长周期光纤光栅(LPG)，其透射谱的中心波长为1574.4nm.FBG的带宽为0.23nm，不受力时其反射波长为1557.98nm，位于LPG的透射谱左沿；当FBG受力时激射波长向长波方向移动，激光通过LPG时透射损耗增大，腔损耗的增加将使激光激射延迟时间增加.因此，应变的大小可以通过激光产生的延迟时间来测量.这种新型应变传感器的分辨率和灵敏度由抽运光脉冲的高、 关键词： 应变传感 光纤激光器 时域测量 光纤Bragg光栅     

同步辐射软X射线源用于软X射线探测元件定标

用于惯性约束聚变诊断的软Ｘ射线探测元器件的能量响应曲线定标，利用北京同步辐射装置（BSRF-3B1束线，束流为20—80mA，光子能量为250—1000eV,通量约为10¹²photon/s·mm²·mr²·0.1%band width）及反射率计靶室，采用AXUV-100硅光二极管作源强绝对监测．对X射线二极管（XRD）及金刚石光电导探测器等五种探测元件进行能量响应曲线定标，获得初步实验结果，并对数据进行了分析 关键词：     

与Λ型三能级原子非共振相互作用的SU(1,1)场的性质

导出了介质中双模SU(1,1)相干态场与Λ型三能级原子非共振相互作用系统的态函数,研究了场模失谐量、克尔介质以及原子初态对场的互关联函数和Mandel Q参量的影响.结果表明:失谐量将削弱光场两模的关联性,并影响场模光子数的统计分布;当SU(1,1)场两模间的光子数之差增大时,失谐量对它们产生的影响变得更弱,此时克尔效应的影响变得明显,它使两模的关联性和光子数的统计分布趋于稳定.     

新型全方位反射铝镓铟磷薄膜发光二极管

提出了一种新型全方位反射铝镓铟磷(AlGaInP)薄膜发光二极管(LED)的结构和制作工艺，在这个结构里应用了低折射率的介质和高反射率的金属联合作为反光镜.用金锡合金(80Au20Sn，重量比)作为焊料把带有反光镜的AlGaInP LED外延片倒装键合到GaAs基板上(RS-LED)，去掉外延片GaAs衬底，把被GaAS衬底吸收的光反射出去.通过与常规AlGaInP 吸收衬底LEDs(AS-LED)和带有DBR的AlGaInP 吸收衬底LEDs(AS-LED(DBR))电、光特性的比较，证明新型全方位反射AlGaInP薄膜LED结构能极大提高亮度和效率.正向电流20mA时，RS-LED的光输出功率和流明效率分别是AS-LED的3.2倍和2.2倍，是AS-LED(DBR)的2倍和1.5倍.RS-LED(20mA下峰值波长627nm)的轴向光强达到194.3mcd，是AS-LED(20mA下峰值波长624nm)轴向光强的2.8倍，是AS-LED(DBR)(20mA下峰值波长623nm)轴向光强的1.6倍. 关键词： 铝镓铟磷 薄膜发光管 全方位反射镜 发光强度     

基于WO3- Pd复合膜的D型光纤光栅氢气传感器

采用磁控溅射方法在侧边抛磨的光纤光栅（D型光纤光栅）上溅射40 nm WO3-Pd复合薄膜,制作了D型光纤光栅氢气传感器.40 nm WO3-Pd复合薄膜是由5 nm的WO3、5 nm的WO3/Pd混合膜和30 nm的Pd 薄膜组成.实验中,首先采用射频溅射技术向D型光纤光栅溅射5 nm WO3薄膜,再利用共溅射技术溅射5 nm WO3/Pd混合膜,最后用直流溅射技术溅射30 nm的Pd薄膜.SEM结果显示在多次通氢气后WO3-Pd薄膜仍然具有较好的表面形貌,这说明WO3-Pd复合薄膜具有较好的机械性能.实验结果表明:该氢气传感器具有较好的重复性,同镀有同样氢气敏感膜的普通FBG相比,D型光纤光栅的灵敏度提高了200%|在氢气体积浓度为6%时,D型光纤光栅传感器的波长变化为15pm.     

Multi-photoactive quantum-dot channels for zinc oxide phototransistors by a surface-engineering patterning process

Red, green, blue (RGB) selective zinc oxide (ZnO) phototransistors with multi-photoactive quantum-dot (QD) channels have been fabricated by a charge-assisted layer-by-layer (LbL) patterning process. QDs were patterned as RGB pixels in multi-photoactive QD channels through the LbL process. The solution-processed ZnO film, which acts as an active-channel layer of the ZnO TFTs, is patterned via a photoinduced surface engineering method to reduce the leakage current of the ZnO TFTs. The average off-current of the patterned ZnO TFTs reduced from 10^?10 to 10^?11 A. QDs absorb visible light and generate photoelectrons, which are then transferred to the ZnO to produce photocurrents. The device shows photoresponsivity of 9.4 mA/W, 12.5, and 137 A/W to the illumination of 638, 520, and 405 nm wavelength light. Our results suggest a promising way to develop an RGB selective phototransistor that uses QDs as a visible light absorption layer and ZnO as an active channel semiconductor.     

Effect of thickness variation of hole injection and hole blocking layers on the performance of fluorescent green organic light emitting diodes

In this paper we present the effect of thickness variation of hole injection and hole blocking layers on the performance of fluorescent green organic light emitting diodes (OLEDs). A number of OLED devices have been fabricated with combinations of hole injecting and hole blocking layers of varying thicknesses. Even though hole blocking and hole injection layers have opposite functions, yet there is a particular combination of their thicknesses when they function in conjunction and luminous efficiency and power efficiency are maximized. The optimum thickness of CuPc (Copper(II) phthalocyanine) layer, used as hole injection layer and BCP (2,9 dimethyl-4,7-diphenyl-1,10-phenanthroline) used as hole blocking layer were found to be 18 nm and 10 nm respectively. It is with this delicate adjustment of thicknesses, charge balancing is achieved and luminous efficiency and power efficiency were optimized. The maximum luminous efficiency of 3.82 cd/A at a current density of 24.45 mA/cm² and maximum power efficiency of 2.61 lm/W at a current density of 5.3 mA/cm² were achieved. We obtained luminance of 5993 cd/m² when current density was 140 mA/cm². The EL spectra was obtained for the LEDs and found that it has a peaking at 524 nm of wavelength.     

Single-longitudinal-mode erbium-doped fiber laser based on a fiber Bragg grating Fabry-Perot filter

A novel single-longitudinal-mode (SLM) erbium-doped fiber laser with a simple linear cavity based on a fiber Bragg grating Fabry-Perot filter (FBG-FPF) and a narrowband (～0.06 nm) FBG is proposed and demonstrated experimentally. Two uniform FBGs form the FBG-FPF, which has two ultranarrow transmission bands with a bandwidth of 0.12 pm and a wavelength spacing of 0.095 nm. By slightly tuning the central wavelength of the narrowband FBG, SLM lasing at 1549.658 or 1549.563 nm (corresponding to the two transmission peaks of the FBG-FPF) is achieved with a laser output power of ～4 mW, when the pump power is ～75 mW.     

Characterization of Gafchromic EBT3 films for ultraviolet radiation dosimetry

A newly released processless Gafchromic EBT3 film was investigated for its response to ultraviolet radiation (UVR) at three different wavelengths: 365 (UVA), 302 (UVB) and 254 nm (UVC). The change in the film's optical density was dependent on the radiance exposure and UV wavelength and was found to correlate with the UV intensity. The dynamic range of the EBT3 films is ～5 to ～60 J/cm² for UVA and UVB and ～5 to ～300 J/cm² for UVC. The dose sensitivity of EBT3 films for UVA and UVB radiation was approximately 10 times higher than that for UVC radiation. The results indicate the suitability of EBT3 films for quantitative and qualitative measurements of UVR exposure.