新型分布式光纤管道泄漏检测技术及定位方法研究

介绍了一种基于萨尼亚克(Sagnac)干涉仪的直线型分布式光纤管道泄漏监测系统,实时进行管道泄漏监测和定位。此系统有两条传感光纤,可有效提高管道监测距离。推导了泄漏信号引起的光信号相位变化表达式;分析了该干涉仪应用于泄漏检测的原理及其泄漏源定位方法,并在分别距两传感光纤末端的法拉第旋转镜为3.990km和4.024 km处进行了泄漏检测实验。管道泄漏实验结果表明,该系统较准确地确定了泄漏源位置且定位误差小于1.05%.     

新型光泵浦垂直外腔面发射半导体激光器

用量子阱技术生长的半导体材料作激光增益介质,AlGaAs/GaAs对做布喇格反射镜,并以简单的平凹腔做谐振腔,半导体激光器作泵浦源,制作出了光泵垂直外腔面发射半导体激光器.在抽运功率1.5 W时,得到了中心波长1005 nm、最大输出功率40 mW的激光,光－光转换效率2.7%.     

Passively Q-switched dual-wavelength Yb:LSO laser based on tungsten disulphide saturable absorber

We demonstrate a passively Q-switched Yb:LSO laser based on tungsten disulphide(WS_2) saturable absorber operating at 1034 nm and 1056 nm simultaneously. The saturable absorbers were fabricated by spin coating method. With low speed, the WS_2 nanoplatelets embedded in polyvinyl alcohol could be coated on a BK7 glass substrate coated with high-refractive-index thin polymer. The shortest pulse width of 1.6 μs with a repetition rate of 76.9 k Hz is obtained. As the pump power increases to 9 W, the maximum output power is measured to be 250 m W, corresponding to a single pulse energy of 3.25 μJ. To the best of our knowledge, this is the first time to obtain dual-wavelength Q-switched solid-state laser using few-layer WS_2 nanoplatelets.     

Observation of self-Q-switching in bulk Yb:GdYSiO laser

We report the first self-Q-switched Yb-doped GdYSiO_5(Yb:GYSO) laser operating at 1080 nm.Stable Q-switched pulses with a repetition rate of 18.1 k Hz and pulse duration of 9.45 μs are obtained.A maximum average output power of452.6 m W is achieved with a 1% transmission output coupler.With a 3% transmission output coupler,the shortest pulse width of 6.6 μs is obtained.It demonstrates that Yb:GYSO crystal can be simultaneously employed as a saturable absorber and a gain medium to generate microsecond Q-switched pulses in the near infrared region.     

掺镱双包层脉冲光纤放大器的特性研究

 在高频及低频脉冲种子光的情况下讨论了掺镱双包层光纤放大器的输出特性.在有限差分法中,对于不同重复频率的脉冲种子光,需要设置不同的初始条件以快速计算得到稳定输出.本文给出了在高频和低频情况下设置初始条件的方法,并讨论了作为种子光的准连续高频高斯脉冲峰值功率与其等效连续光功率之间的关系,最后计算了种子光为高频及低频脉冲情况下的平均输出功率与泵浦功率的关系.     

Self-assembly of gold nanoparticles into nanoholes through annealing in the fabrication of square lattices of nanocylinders

We demonstrate the self-assembly of solution-processible gold nanoparticles into the nanoholes consisting of patterned substrate through annealing,which facilitates successful fabrication of square lattices of gold nanocylinders with a period of 350 nm,a height of about 200 nm,and an aspect ratio larger than 2.     

不同零色散点光子晶体光纤的超连续谱产生

本文实验研究了飞秒脉冲在不同零色散点光子晶体光纤中传输时产生超连续谱的现象。首先,我们通过非线性薛定谔方程理论计算了激光脉冲分别在正、负色散光子晶体光纤中传输时产生的超连续谱;计算结果表明在正色散光子晶体光纤产生的超连续谱远远大于在负色散中产生的超连续谱。其次,在实验上采用零色散点分别为800 nm、1 060 nm和2 000 nm的光子晶体光纤,将脉宽为130 fs,中心波长800 nm,脉冲重复频率为80 MHz的脉冲输入这些光纤中产生超连续谱并研究其特性,实验结果表明光子晶体光纤的零色散点越小,在其中产生的超连续谱越宽越平坦。同时产生的超连续谱也与激光脉冲的能量和中心波长相关。     

自锁模Cr4+∶YAG激光器的色散补偿研究

从棱镜对补偿色散的原理出发,介绍了Cr4+∶ YAG锁模激光器中色散补偿的特点,发现熔融石英作为色散补偿元件,不仅可以完全补偿二阶色散,而且三阶色散也得到了一定的补偿,并得到了脉冲宽度最小为65 fs,中心波长为1520 nm,重复频率为120 MHz的脉冲序列.     

Round-trip Dispersion Calculation for Martinez Pulse Stretcher

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｃｈｉｒｐｅｄ ｐｕｌｓｅａｍｐｌｉｆｉｃａｔｉｏｎ (ＣＰＡ )ｈａｓｂｅｃｏｍｅａｓｔａｎｄａｒｄｔｅｃｈｎｉｑｕｅｆｏｒｕｌｔｒａｓｈｏｒｔｐｕｌｓｅａｍｐｌｉｆｉｃａｔｉｏｎｓ.ＩｎｃｏｎｖｅｎｔｉｏｎａｌＣＰＡｓｙｓｔｅｍｓ ,ｔｈｅｓｅｅｄｐｕｌｓｅｓａｒｅｅｘｐａｎｄｅｄｉｎｔｉｍｅｂｙｐａｓｓｉｎｇｔｈｒｏｕｇｈａｓｔｒｅｔｃｈｅｒ.Ｔｈｅａｍｐｌｉｆｉｅｄｐｕｌｓｅｉｓｔｈｅｎｒｅｃｏｍｐｒｅｓｓｅｄｔｏｔｈｅｏｒｉｇｉｎａｌｐｕｌｓｅｄｕｒａｔｉｏｎｂｙ…     

双向稳定传输的有耗色散补偿光纤链的数值模拟

本文以平均近似法处理光纤链的损耗理论为前提,采用一组非零色散位移光纤链的参量,用分步傅里叶方法对20Gb/s,1000km的归零码光脉冲进行了数值模拟.数值结果表明,在该光纤链上可实现双向准稳传输,并讨论了三阶色散对光脉冲传输的影响.