基于PD-MSM-Lyot 滤波器的多波长掺铒光纤激光器

提出了一种基于偏振依赖多模- 单模- 多模光纤Lyot (PD-MSM-Lyot) 滤波器的 多波长掺铒光纤激光器。PD-MSM-Lyot 光纤滤波器由一个PD-MSM 滤波器和一段保偏光 纤构成,其相邻滤波通带具有相同波长间隔。充分利用偏振依赖MSM 光纤滤波器的起 偏作用并结合腔内色散位移光纤中的非线性偏振旋转效应, 构成了强度相关损耗机 制, 从而抑制掺铒光纤中的增益竞争作用, 获得了室温下19 个波长间隔为0.2 nm 的密 集多波长激光输出。通过对比可得, 输出激光光谱随泵浦功率增大而变的更平坦, 且 波长数更多。     

一种高斯型ASE光源研究

简单介绍了掺铒光纤的光放大原理,分析了四种ASE光源的光路结构。针对双通前向结构,设计了一种适用高精度光纤陀螺仪的高斯型ASE光源,并进行了试验研究。试验结果表明,掺铒光纤的掺杂浓度、光纤长度都对ASE光源的输出特性具有很大的影响。此外,根据试验结论,研制出高斯型ASE光源,其性能稳定,已在多个高精度光纤陀螺仪型号上实现了实际应用,并取得了良好的效果。     

中航工业成功研制光纤飞秒激光器 技术国内领先

<正>近日,中航工业飞秒激光课题组成功研制1.03μm掺镱光纤飞秒激光器和1.55μm掺铒光纤飞秒激光器。这标志着计量所在腔内色散补偿光纤激光技术方面达到了国内领先水平,也为实现小型化便携式的飞秒激光频率梳奠定了良好的开端基础。以光纤飞秒激光频率梳为核心的精密光谱源标准装置的建立,不仅为我国国防、军事等领域广泛应用的红外激光源提供精密的校准测试服务,而且为将来便携式激光跟踪仪、小型化激光雷达等高新武器提供更精密的激光源。此外,光纤激光频率梳的研究还可改进     

中航工业计量所成功研制光纤飞秒激光器

正近日,中航工业北京长城计量测试技术研究所(简称中航工业计量所)重点实验室飞秒激光课题组成功研制1.03μm掺镱光纤飞秒激光器和1.55μm掺铒光纤飞秒激光器。这标志着中航工业计量所在腔内色散补偿光纤激光技术方面达到了国内领先水平,也为实现小型化便携式的飞秒激光频率梳奠定了良好的开端基础。光纤飞秒激光器以其小型化、便携化、风冷却、低成本和     

UDWDM光纤通信及其关键技术分析

分析了波分复用(WDM)光纤通信的工作原理和应用特点,重点分析了目前研究中的超密集波分复用(UDWDM)光纤通信中的光源波长稳定技术、复用/去复用技术、掺铒光纤放大器(EDFA)和光纤的性能改善技术等关键技术.     

非线性光纤Sagnac干涉仪精度分析研究

非线性光纤Sagnac干涉仪具有突破标准量子极限的优点,可实现超高精度地球自转角速度的测量。通过理论建模和数值仿真,阐明了非线性光纤Sagnac干涉仪的增益系数、光纤环长度、光纤环面积和激光波长等参量对干涉仪精度的影响。在测量地速的条件下,光纤环半径取0.5m,光纤环长度为20km且非线性增益系数大于3.582时,干涉仪灵敏度能够达到10－6(°)/h(量级),为实现高灵敏度非线性光纤Sagnac干涉仪提供了支撑。     

光频测量用飞秒激光频率梳光谱扩展实验研究

在光频的绝对测量研究中,本研究小组研制了光谱范围为650~950 nm波段、重复频率为350 MHz的"单块"结构钛宝石飞秒激光频率梳。为了实现其对633 nm波长国家副基准频率的绝对测量,本实验分别采用棱镜对和啁啾镜对进行脉宽压缩,然后注入光子晶体光纤进行光谱扩展。实验发现两者均可扩展出短波长方向的光谱,但棱镜对扩谱结构由于具有较长的"光程臂长"容易受到扰动而造成光纤耦合的不稳定,最终表现为光谱中各波长成分的光强不稳定而无法用于光频测量。啁啾镜对结构紧凑、稳定性强,经过脉宽压缩及光子晶体光纤扩谱,最终获得了光谱覆盖600~950 nm波段、各波长成分强度稳定、各光频齿频率稳定度同步于氢原子钟的可用于光频测量的飞秒激光频率梳     

典型激光波长对纳秒激光烧蚀铝靶冲量耦合特性的影响

为研究532nm和1064nm两种典型激光波长对纳秒脉冲激光烧蚀铝靶冲量耦合特性的影响,在建立的热传导模型和羽流膨胀流体动力学模型基础上,加入了在激光烧蚀过程中靶材吸收系数、热导率和反射率等光学和热物理参数的变化,考虑了形成的等离子体羽流对入射激光的屏蔽作用因素影响,从而建立了一个复杂的一维纳秒激光烧蚀铝靶冲量耦合物理模型。通过计算,获得了两种激光波长辐照下,烧蚀过程中烧蚀参数和物理参数的变化,分析等离子体羽流对入射激光的屏蔽效应,进一步分析得到对冲量耦合特性的影响。结果表明:短波长激光不仅有利于激光与靶材的能量耦合,同时,短波长激光辐照下形成的等离子体羽流对短波长入射激光吸收率也较低,有利于提高靶的冲量耦合;在等离子体形成初期,即等离子体吸收率较低时,分别达到两种激光波长辐照下的最优冲量耦合。     

用于高清视频信号传输的单通道旋转连接器

本文基于C-lens准直器耦合原理设计一种单通道光纤旋转连接器以满足现有高清视频信号传输的需求。为了提高信号耦合效率,优化了C-lens透镜点精度,测试了研制的单通道光纤旋转连接器的插入损耗与损耗旋转变化量。实验表明:当输入波长为1550nm时,连接器插入损耗为0.82dB,损耗旋转变化量在0.29dB,满足大容量信号的传输要求。基于设计的光纤旋转连接器搭建了高清视频信号传输实验,发现该器件的视频传输速率达到2.97Gbps,具有良好的高清、高速视频信号传输的能力。     

高功率低偏振度光纤陀螺光源技术

针对高精度光纤陀螺对ASE光源高功率、宽谱宽和低偏振度的应用需求,设计了双程后向ASE光源并进行了仿真和实验验证,研究了铒纤长度为4m、10m和19m的光源光谱特性,分析了泵浦功率、温度的变化对输出功率、平均波长及光谱宽度等参数的影响。结果表明,当铒纤长度为19m时,光源在驱动电流为110mA时的输出功率为4.055mW,光谱宽度为16.63nm,偏振度为1.925%,平均波长随电流的变化量为9.9×10-6/mA。同时,温度实验表明,铒纤长度为19m的光源平均波长随温度的变化量为5.9×10-6/℃。     

Experimental investigation of laser peening on TiAl alloy microstructure and properties

In order to study the effect of laser peening on microstructures and properties of Ti Al alloy, Ti Al alloy samples were treated by Nd:YAG laser system with the wavelength of 1064 nm,pulse-width of 18 ns, and pulse-energy of 0–10 J. Surface micro-hardness, roughness, and microstructural characteristics were tested with micro-hardness tester, roughness tester and scanning electron microscope. Residual stress and pole figures were tested with X-ray diffraction and its high-temperature stability was analyzed. The experimental results show that surface micro-hardness increases by up to 30%, roughness increases to 0.37 lm, compressive residual stress increases to 337 MPa, and local texture and typical lamellar microstructure are generated. Residual stress, micro-hardness, and(002) pole figures tests are conducted, compressive residual stress value drops from 337 MPa to 260 MPa, hardness value drops from 377 HV_(0.2) to 343 HV_(0.2), and the(002)poles shift back to the center slightly. Laser peening improves microstructure and properties of Ti Al alloy significantly.     

Optimum Mismatched Filters for Sidelobe Suppression

This paper discusses the application of least-mean-squares approximate inverse filtering techniques to radar range sidelobe reduction. The method is illustrated by application to the 13-element Barker code. The performance of the least-mean-square inverse filter is compared with the matched filter and with the simplified sidelobereducing filters of Rihaczek and Golden. A filter which completely suppresses the range sidelobes of a 13-element Barker sequence is only 0.2 dB worse than a matched filter in noise.     

Galileo Ultraviolet Spectrometer experiment

The Galileo ultraviolet spectrometer experiment uses data obtained by the Ultraviolet Spectrometer (UVS) mounted on the pointed orbiter scan platform and from the Extreme Ultraviolet Spectrometer (EUVS) mounted on the spinning part of the orbiter with the field of view perpendicular to the spin axis. The UVS is a Ebert-Fastie design that covers the range 113–432 nm with a wavelength resolution of 0.7 nm below 190 and 1.3 nm at longer wavelengths. The UVS spatial resolution is 0.4 deg × 0.1 deg for illuminated disc observations and 1 deg × 0.1 deg for limb geometries. The EUVS is a Voyager design objective grating spectrometer, modified to cover the wavelength range from 54 to 128 nm with wavelength resolution 3.5 nm for extended sources and 1.5 nm for point sources and spatial resolution of 0.87 deg × 0.17 deg. The EUVS instrument will follow up on the many Voyager UVS discoveries, particularly the sulfur and oxygen ion emissions in the Io torus and molecular and atomic hydrogen auroral and airglow emissions from Jupiter. The UVS will obtain spectra of emission, absorption, and scattering features in the unexplored, by spacecraft, 170–432 nm wavelength region. The UVS and EUVS instruments will provide a powerful instrument complement to investigate volatile escape and surface composition of the Galilean satellites, the Io plasma torus, micro- and macro-properties of the Jupiter clouds, and the composition structure and evolution of the Jupiter upper atmosphere.     

Microacoustic Imaging Technique for Bulk Microstructure Characterization of Woven CFRC Materials

In short wavelength case ultrasound propagation through woven carbon fiber-rein-forced composite (CFRC) materials essentially depends on their microstructure.Fiber bundle and weaving ply can be considered as basic structural elements of woven CFRC laminates.These structural units provide effective reflectors when ultra-short impulse high frequency ultrasound impinges on woven laminates.The reflection coefficient R0 achieves level of 3%-15% at ply-ply interface,0.2-0.4 in resin pocket region.This magnitude of reflection coefficient offers reasonable acoustic contrast to see packing,lay-up and resin pockets in woven laminate body by acoustic imaging methods.Microacoustic imaging technique is based on time-resolved echoes from reflections in woven CFRC laminates.A focal system with low aperture angle is used to generate 20-40 probe ultrasonic pulse wave.Its spatial resolution is up to 60mm at 50MHz in woven CFRC laminate.The results presented in this paper demonstrates the possibility and potentiality of characterization of microstrueture of woven CFRC laminates.Packing,lay-up,weaving nature,fiber bundle,resin pocket as well as their topology are exhibited clearly in the acoustic images by using microaeoustic technique.     

Surface micro-texture on sapphire fabricated by laser ablation trajectory regulation

Fabrication of the surface micro-texture on the C-plane sapphire is undertaken by a355 nm Ultraviolet(UV) pulsed laser. The surface micro-textures of sapphire with different laser scanning line spacing ranging from 10 lm to 100 lm are obtained, where the selection range of scanning line spacing is controlled in the range of the groove width and plasma width to obtain a surface of high Peak-Valley(PV) value. A reasonable processing order is proposed to manufacture different types of surface micro...     

Fiber lasers: A future technology for lasers in space

The constraints of operation in space have largely precluded the use of conventional solid-state laser systems for applications including remote sensing, communication relays, and active laser radars. A new technology, fiber lasers, may offer all of the needed features at an affordable price. An appealing aspect of the fiber laser is that it does not need a rigid optical bench. Only the output end of the fiber need be held in rigid reference to the optical tracking system. Design, fabrication, and testing of the laser resonator is generally the most expensive and longest lead part of the effort for conventional solid-state lasers. Advances in fiber optic technology and devices mean that the "fiber laser" need not be a simple device but may be a complex system employing sophisticated technology, such as wavelength selective Bragg reflectors and nonlinear optical frequency shifters. Three companies have obtained single-mode outputs of 35 - 40 watts single mode at 1.03 - 1.1 mu.     

背带式双波长全固态激光清洗设备

介绍了一种背带式18W全固态1064nm/532nm双波长激光清洗设备,其中,532nm绿光功率为6.4W,M2=2,不稳定度小于1%。针对表面油漆涂层和铁锈进行了清洗试验,并给出了清洗工件的金相图,结果表明能够满足工业清洗的要求。     

Fiber lasers: a future space technology

The constraints of operation in space have largely precluded the use of conventional solid-state laser systems for applications including remote sensing, communication relays, and active laser radars. A new technology, fiber lasers, may offer all of the needed features at an affordable price. An appealing aspect of the fiber laser is that it does not need a rigid optical bench. Only the output end of the fiber need be held in rigid reference to the optical tracking system. Design, fabrication, and testing of the laser resonator is generally the most expensive and longest lead part of the effort for conventional solid-state lasers. Advances in Fiber Optic technology and devices mean that the "fiber laser" need not be a simple device but may be a complex system employing sophisticated technology such as wavelength selective Bragg reflectors and nonlinear optical frequency shifters. Three companies have recently obtained single-mode outputs of 3540 watts single mode at 1.03-1.1 microns.     

倍频激光分离膜的损伤特性研究

从激光分离膜的热损伤原理出发,建立了1064nm波长激光分离膜的损伤方程,并给出了损伤阈值的求解过程,在理论上分析了1064nm波长激光对SiO2薄膜材料的损伤特性;文中运用仿真方法得出激光照射过陧中薄膜内温度场随杂质位置不同的分布曲线。