Pulsed infrared radiation transmission through chalcogenide glass fibers

Two different kinds of chalcogenide glass IR fibers were evaluated relative to transmission of pulsed IR radiation produced by several laser sources in the wavelength range from 1 to 10 μm. Fibers composed either from As-Se-Te or from As₂S₃ glass, of 250, 500, 750 and 1000 μm and 250, 750 and 1000 μm core diameters were studied, respectively. Attenuation measurements were obtained as a function of the laser energy input and as a function of curvature, wherever this was possible. The output beam quality was also studied using a beam profiler. The lasers used were a Q-switched Nd:YAG laser, emitting at 1.06 μm, a free-running or Q-switched Er:YAG laser emitting at 2.94 μm and a tunable pulsed CO₂ laser emitting in the range of 9.3-10.6 μm. The fibers exhibited better behavior when tested with the Er:YAG laser and they were found fragile in pulsed radiation from the Nd:YAG and the CO₂ laser. The output beam profiles generally showed a central multi-spiking energy distribution.     

Zig-Zag板条泵浦的2.12μm激光器

 为了实现窄脉宽、高峰值功率2.12 μm激光的稳定输出,设计了基于侧面泵浦Zig-Zag 板条产生1.06 μm基频光,进而泵浦KTP晶体通过II类相位匹配产生2.12 μm激光的光参量振荡实验。对外腔及内腔进行了实验研究,分别获得了1.53%和2.86%的电光转换效率。在20 Hz频率下内腔2.12 μm输出能量达到70 mJ以上,脉宽7 ns~9 ns。其中内腔实验中能量输出稳定度接近8%。     

环形腔2.05μm单谐振KTP晶体光参量振荡器研究

针对大气CO_2浓度探测差分吸收激光雷达的应用需求,采用稳定环形腔和模式匹配设计,搭建了一套单纵模1 064nm激光泵浦的单谐振KTP晶体光参量振荡器,获得高斜率转换效率、基横模的2.05μm波长纳秒激光脉冲输出.在8字形环形行波稳定腔中,将2块II类相位匹配KTP晶体以走离补偿方式放置,在20Hz重复频率下,当泵浦单脉冲能量达到11mJ时,获得了单脉冲能量为2.4mJ的2.05μm信号光输出,脉宽约24ns,斜率效率达到53%.2.05μm信号光光束质量因子在x、y方向分别为1.3和1.2.     

国产光纤实现直接抽运全光纤化3000 W级激光输出

基于国产光纤构建了直接抽运全光纤化主控振荡器功率放大器结构光纤激光器, 放大级分别采用武汉烽火锐光科技有限公司和中国电子科技集团公司第四十六研究所提供的国产20/400 μm掺镱双包层光纤作为增益光纤, 通过全国产化放大级实现了3050和3092 W的1080 nm激光输出. 放大级提取效率分别为67.3%和68.2%, 光-光效率分别为63.0%和63.9%. 据可查询资料, 这是公开报道的直接抽运全光纤激光输出的最高水平, 同时由于采用了国产光纤作为放大级增益光纤, 表明国产光纤具备了3 kW级光纤激光器输出能力. 通过国产光纤横截端面以及光纤熔接显微镜图像实验分析知, 光纤制造工艺的不足是导致国产光纤激光器效率低的主要原因. 继续改进光纤工艺, 提升抽运功率, 优化光纤长度, 有望实现更高功率的全国产化光纤激光器输出.     

用大芯径石英玻璃光纤传输兆瓦级高能激光脉冲及其在双波长LA-LIBS技术中的应用

为了解决单脉冲激光诱导击穿光谱(LIBS)技术在元素分析时空间分辨本领与分析灵敏度之间的矛盾,本文利用一台双波长输出的Nd∶YAG激光器开展了双波长激光剥离-激光诱导击穿光谱(LA-LIBS)技术的研究。其中532 nm的二倍频激光用于剥离样品;1 064 nm的基频激光通过大芯径石英玻璃光纤传输并实现一定的延时后用于击穿被剥离的样品。两束激光采用正交几何配置以实现高空间分辨高灵敏的元素分析。实验研究了1 064 nm激光到光纤的耦合、光纤输出后的准直以及再聚焦时的一些关键技术问题。研究并得出了四种不同光纤对激光能量的传输能力。选择利用芯径为800 μm,数值孔径为0.39、长50 m的石英玻璃光纤成功传输了15 mJ的调Q激光脉冲并实现了250 ns的延时。并在此基础上开展了铜合金样品的双波长LA-LIBS分析,实验验证了基于一台Nd∶YAG激光器开展双波长LA-LIBS研究的可行性。该技术只需要一台激光器就可以完成相应的光谱分析,具有系统结构简单,便于小型化等优点,适合对不同样品开展原位的高空间分辨高灵敏的元素显微分析。     

高峰值功率1．57μm脉冲激光器的研究

KTP非线性频率转换技术是实现人眼安全激光的有效方法,为了获得高峰值功率人眼安全激光,设计了一种级联式1．06μm泵浦非临界相位匹配环形腔KTP光参量振荡器一光参量放大器,并对其激光输出进行了测试,结果证明该光参量振荡器输出激光波长1．571μm,激光峰值功率42MW,光光转换效率35％,能量稳定度2．5％。该技术已用于计量检测标准光源,并在远程人眼安全激光测距仪、激光雷达等装备中具有应用前景。     

Infrared-laser delivery system based on polymer-coated hollow fibers

Infrared Er : YAG laser delivery systems based on hollow fibers with an internal polymer layer has been developed. The system consists of a hollow fiber as the delivery medium, a launching coupler for effective coupling between the laser beam and the fiber, and a sealed hollow-fiber tip attached at the output end of the fiber. Fabrication process of the fiber and attachment of the delivery system is reported.     

电光调Q脉冲Ho:YLF激光器实验研究

2μm低重复频率高峰值功率高光束质量激光在中长波光参量非线性频率变换等领域具有较为广阔的应用前景。采用L型谐振腔结构,使用42 W的掺Tm光纤激光器泵浦Ho:YLF晶体。基于磷酸钛氧铷（RTP）电光调Q技术,实现了重复频率50 Hz、脉冲宽度18 ns、脉冲能量13.5 mJ、峰值功率0.75 MW的2.05μm Ho:YLF固体激光输出。光束的水平方向和竖直方向M2因子分别为1.4和1.1。该Ho:YLF固体激光器采用光纤激光器泵浦,具有结构紧凑的特点,为更高能量的Ho激光输出奠定了基础。     

激光二极管泵浦NYAB激光器的空间分布速率方程的研究

报道了用以描述激光二极管泵浦ＮＹＡＢ连续激光顺空间分布特性的非线性耦合的速率方程组，和以此方程组进行的理论计算，讨论了泵浦光和激光的空间分布、晶体的最佳长度、输出镜的最佳透过率对激光器输出的影响，给出了ＮＹＡＢ激光器设计的一些依据。     

26 mJ, 130 W Q-switched fiber-laser system with near-diffraction-limited beam quality

We demonstrate a Q-switched fiber laser system emitting sub-60 ns pulses with 26 mJ pulse energy and near-diffraction-limited beam quality (M2<1.3). In combination with a repetition rate of 5 kHz, a corresponding average output power of 130 W is achieved. This record performance is enabled by a large-pitch fiber with a core diameter of 135 μm. This fiber allows for effective single-mode operation with mode field diameters larger than 90 μm even at average output powers exceeding 100 W.     

Short Tm3+-doped fiber lasers with watt-level output near 2 μm

High-power operation of diode-pumped fiber lasers at wavelength near 2μm are demonstrated with short length of heavily Tm3 -doped silica glass fibers. With 7-cm long fiber, a laser at near 2 μm is obtained with the threshold of 135 mW, maximum output power of 1.09 W, and slope efficiency of 9.6% with respect to the launched power from a laser diode at 790 nm. The output stability of this fiber laser is within 5%.The dependence of the performance of fiber lasers on the operation temperature and cavity configuration parameters is also investigated.     

高功率TEA CO2激光器两波长激光切换输出技术

 以TEA CO₂激光器通常采用的平-凹光学稳定腔为基础,提出了一种新的波长选支方法——输出窗口镀膜选支方法。利用一台高平均功率TEA CO₂激光器进行了选支实验研究,结合现有光学镀膜技术,得到了中心波长为9.3 μm的激光单谱线输出,其单脉冲能量及平均功率与激光器原中心波长10.6 μm单谱线输出的相应参数基本相当。研究发现,以相同单脉冲能量激光照射热敏纸时,中心波长9.3 μm激光光斑与中心波长10.6 μm的明显不同。同时,还设计出两波长窗口密闭免调切换装置,在一台激光器上实现了10.6,9.3 μm两个中心波长激光同等功率水平的免调切换输出,切换位置误差小于5″,密封性能满足使用要求。     

Fiber Optic Coupling of CW Linear Laser Diode Array

Based on a set of microoptics the output radiation from a continuous wave (CW) linear laser diode array is coupled into a multi-mode optical fiber of 400 μm diameter.The CW linear laser diode array is a 1 cm laser diode bar with 19 stripes with 100 μm aperture spaced on 500 μm centers.The coupling system contains packaged laser diode bar,fast axis collimator,slow axis collimation array,beam transformation system and focusing system.The high brightness,high power density and single fiber output of a laser diode bar is achieved.The coupling efficiency is 65% and the power density is up to 1.03×104 W/cm2.     

非临界相位匹配KTP光学参量振荡器的研究

对电光调Q(Ce,Nd):YAG激光抽运内腔非临界相位匹配(NCPM)光参量振荡器(IOPO)进行了实验研究,实验发现IOPO输出光波长为532 nm、632 nm、1 064 nm、1 100 nm和1 571 nm 5种。OPO输出镜对信号光反射率较大时,信号光出现多脉冲,可以通过控制信号光反射率,使信号光为单脉冲。信号光能量随着抽运能量增加到一定值后出现饱和。     

平面光波导型单纤三向器的研究

利用光束传输法,分析设计了一种只由两个定向耦合器构成、能直接与单模光纤相耦合、易于集成的平面光波导（Planar Lightwave Circuit,PLC）型1.31/1.49/1.55 μm单纤三向器.该器件的输入输出弯曲波导和耦合区平行波导均采用光束传输法进行优化设计,并对器件的折射率进行了容差分析,获得了当两个定向耦合器的耦合长度分别为6 578 μm、3953 μm时,器件对各波长的隔离度均在47 dB以上,且插入损耗小于0.05 dB.     

Fiber Optic Coupling of CW Linear Laser Diode Array

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包层泵浦的高功率掺铥光纤激光器

研究了一种输出功率高且光束质量好的包层泵浦的掺铥光纤激光器.当泵浦功率达到30 W时,该掺铥光纤激光器产生的最大输出功率是6.1 W,且波长在2 μm左右,斜率效率达到55.6%,产生激光的阈值是2.2 W.当输出功率为3.3 W时,测得光束质量M2X和M2Y分别为1.26和1.32.     

脉冲式2 μm KTiOAsO4光参变振荡器

为了验证KTiOAsO4(KTA)晶体用于光参变振荡产生2μm激光的可行性,设计了脉冲式2μm KTA光参变振荡器,采用θ=49°切割的KTA晶体作为光参变振荡晶体,实现了2μm激光的输出;计算了该系统在双谐振情况下的起振阈值,在实验中测得输出的信号光、闲频光波长在2.16μm和2.09μm附近,与理论计算基本吻合,并测量了脉冲宽度。同时选用了对信闲光透过率分别为60%、70%、90%的镜片作为光参变振荡器(OPO)输出镜,测得了三种情况下的输出能量及电光效率的数值;测得了在380 V电压下,输出镜透过率一定时输出能量与光参变振荡器腔长之间的关系曲线,从而验证了KTA晶体用于光参变振荡产生2μm激光的可行性,为下一步的研究工作打下了基础。     

Internal Optical Parametric Oscillator with SBS Phase Conjugate Resonator

It is reported a novel optical parametric oscillator with KTP as medium crystal inside a Nd∶YAG phase conjugate resonator. In the phase conjugate resonator, the laser beam quality is promoted by phase-conjugate mirror, which is realized by stimulated Brillouin scattering effect, and Q-switch is generated simultaneously. With this device, the laser output at 1.57 μm with 15 mJ energy and 8 ns pulse width is obtained.     

Internal Optical Parametric Oscillator with SBS Phase Conjugate Resonator

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