频率分辨光学开关法测量飞秒脉冲的研究

在详细分析频率分辨光学开关法(FROG)的基础上,对几种类型的FROG迹线进行了模拟,并运用Matlab软件编制程序还原出脉冲信息。用二次谐波型频率分辨光学开关法(SHG-FROG)测量了KLM钛宝石激光器的输出脉冲,并运用算法进行了处理,得到脉冲的振幅和相位信息,与干涉自相关法的测量结果一致。     

Propagation of Ultra-fast Femtosecond Pulses in Silicon-on-insulator Optical Waveguides

A complete theoretical modeling, avoiding any priori-assumption, is deduced and demonstrated for ultra-fast femtosecond optical pulses in silicon-on-insulator optical waveguides which includes the group velocity dispersion, third-order dispersion, self-phase and cross-phase modulations, self-steepening and shock formation, Raman depletion, propagation loss, two-photon absorption, free-carrier absorption, and freecarrier dispersion. Finally, the temporal and spectral characteristics of 100 fs optical pulses at 1. 55 μm are numerically observed in 5-mm-long waveguides while considering different initial chirps and incident peak intensity levels.     

飞秒脉冲测量技术的新进展

本文综述了超快激光领域中测量技术的最新发展，特别详细地论述了目前国际上公认的测量脉冲位相的2种标准方法；FROG和SPIDER的基本原理、实验构成和性能比较。     

用于飞秒脉冲激光腔内的啁啾镜的优化设计

介绍了啁啾镜的基本原理和优化设计思想 ,阐述了优化设计的基本过程 ,并通过计算机优化计算了啁啾镜设计。具体分析了影响啁啾镜色散补偿特性的几个主要因素 ,如色散量、色散带宽、膜层数以及膜层的厚度变化对啁啾镜光学特性造成的影响。其中色散量的控制和色散带宽的选择是最重要的优化设计指标     

高阶非线性效应下飞秒光脉冲间的相互作用

研究了光纤通信中高阶非线性下飞秒光脉冲间的相互作用。数值结果表明:自频移和 自陡峭都使脉冲向后沿呈现非线性的偏移,前一个脉冲的偏移量很小,基本上是呈线性偏移,后一个脉冲随传输距离的增加,偏移量逐渐的增大,呈非线性偏移。二脉冲在传输的过程中,前一个脉冲的峰值强度逐渐地减小,后一个脉冲的峰值强度逐渐地增加。在自频移和自陡峭的共同作用下,后一个脉冲在相同的传输距离内偏移量较之它们单独存在时大得多,同时脉冲间能量的转移也变快。三脉冲和四脉冲间的相互作用具有类似的结果。     

基于半导体激光器的皮秒非接触电光采样系统

建立了基于增益开关半导体激光器的非接触电光采样系统。利用电光晶体的Ｐｏｃｋｅｌｓ效应．以ＬｉＴａＯ３晶体制做成微小的电场传感器，对梳状波信号进行了测试。实验结果与取样示波器测得结果相符。系统的时间分辨率为２５ｐｓ．最小可测电压为２０ｍＶ。     

飞秒激光在多孔光纤中传输特性的研究

介绍了多孔光纤的特性以及对飞秒激光在多孔光纤中传输特性的研究。     

飞秒强激光脉冲激发下Ta2O5薄膜光学常量的瞬态变化

用抽运-探测方法研究了Ta2O5单层膜在预损伤(60%损伤阈值)的抽运强度下反射和透射率的瞬态变化.观察到其峰值出现在抽运后约100fs处,然后以约600fs的时间常量衰减.用单层吸收膜加透明衬底的理论模型对实验结果进行拟合,得出光学参量(折射率n和消光系数k)瞬态变化的峰值为An=-3.4%和△k=0.042,对应吸收系数增大了3个数量级.     

频率分辨光学开关法测量飞秒脉冲

阐述了频率分辨光学开关法测量飞秒脉冲的原理,详细分析了模式尺寸效应和非线性效应对飞秒脉冲测量的影响.构建了一台用于飞秒脉冲测量的二次谐波-频率分辨光学开关装置,利用该装置对谐振腔输出的飞秒脉冲及压缩后的脉冲进行了测量.得到了飞秒脉冲的时间宽度及光谱宽度、电场及其相位在时域和频域的详细信息.谐振腔直接输出脉冲的时间宽度为56 fs,光谱宽度为27 nm,时间带宽积为0.686,算法中的最小误差为0.001792.脉冲压缩后的测量结果为27 fs,光谱宽度为92 m,时间带宽积为1.27,算法误差为0.0093289.     

光学玻璃在皮秒与飞秒脉冲激光作用下的暗化现象

研究了某些光学玻璃在皮秒和飞秒激光照射下产生的暗化 (darking)特性。测量了玻璃在 810nm飞秒激光照射前后的吸收光谱 ,并进行了比较与分析。玻璃在超短脉冲激光照射后发生暗化 ,是因为玻璃内生成色心的结果。同时提出了解释超短脉冲飞秒激光引起玻璃产生色心的机理。上述暗化具有热擦除性 ,在 2 0 0℃下热处理几分钟后 ,暗区消失     

飞秒激光脉冲序列互相关的数值模型与分析

为研究飞秒激光超短脉冲序列在空气中传输的时间相干特性,根据飞秒脉冲序列的传播理论和空气折射率Ciddor公式,建立了飞秒激光脉冲序列间脉冲在空气中传播的互相关数值模型。根据该模型可以得到不同光谱分布、不同光程差和不同大气条件下的飞秒脉冲序列间脉冲的互相关图形。数值模拟结果表明随着脉冲间光程差的增大,由于色散的原因,互相关图形加宽和啁啾,并且峰能量减小;然而当光程差不变,仅改变大气条件时,互相关图形仅仅作线性移动,没有任何额外线性加宽或啁啾。飞秒光学频率梳具有非常高的时间相干性,并且飞秒脉冲间的互相关图形只取决于激光器光源的光谱分布。     

具有几个光振荡周期长的飞秒脉冲在单模光纤中的传输

发展了飞秒光脉冲在光纤中的传输理论,给出了具有几个光振荡周期长的飞秒脉冲在单模光纤中的传输方程,对方程作了数值解,模拟了具有几个光振荡周期的飞秒脉冲在单模光纤中的非线性传输。     

Femtosecond Laser Application to PLC Optical Devices and Packaging

Using tightly focused femtosecond laser pulses, we produce an optical waveguide and devices in transparent materials. This technique has the potential to generate not only channel waveguides, but also three‐dimensional optical devices. In this paper, an optical splitter and U‐grooves, which are used for fiber alignment, are simultaneously fabricated in a fused silica glass using near‐IR femtosecond laser pulses. The fiber‐aligned optical splitter has a low insertion loss, less than 4 dB, including an intrinsic splitting loss of 3 dB and excess loss due to the passive alignment of a single‐mode fiber. Finally, we present an output field pattern, demonstrating that the splitting ratio of the optical splitter becomes approximately 1:1.     

Position Effect of Spectral Filter on Properties of Highly Chirped Pulses in an All-Normal-Dispersion Fiber Laser

Numerical studies on the position effect of spectral filter (SF) in an all-normal-dispersion fiber laser are presented in this paper. The dependence of the available bandwidth range of the SF on its position in the laser cavity is investigated. Our simulation results suggest that the output pulses with high energy and strong peak power can be obtained when the SF with an appropriate spectral bandwidth is placed at the optimal positions in the laser cavity.     

飞秒激光脉冲二阶干涉自相关法测量及其精细结构研究

本文用二阶相干自相关法测量飞秒激光脉冲宽度，测量过程完全由计算机控制和完成，测量精度达０．３飞秒。并分析了测量曲线的精细结构，发现其精细结构主要是由基频光相干场的振动频率所决定。     

飞秒激光光谱位相干涉仪的数值模拟与分析

对用光谱位相相干直接电场重建法 (SPIDER)测量飞秒光脉冲啁啾特性的光谱位相干涉仪进行了数值模拟 ;对假设具有不同类型啁啾的飞秒脉冲进行光谱位相重构 ,还原出时域脉冲强度包络和位相 ,并与实验结果进行了比较     

10fs以下的飞秒激光脉冲的非线性传输

给出了具有几个光振荡周期长的飞秒激光脉冲在不考虑群速色散的情况下传输方程的解,用数值方法模拟了飞秒激光脉冲的非线性传输,考察了非线性效应对脉冲形状和频谱的影响,得到和慢变振幅近似下不完全一致的结论。     

Influence of Two-Photon Absorption Anisotropy on Terahertz Emission Through Optical Rectification in Zinc-Blende Crystals

We report for the first time on the observation of an angular anisotropy of the THz signal generated by optical rectification in a < 111 > ZnTe crystal. This cubic (zinc-blende) crystal in the <?111 > orientation exhibits both transverse isotropy for optical effects involving the linear χ⁽¹⁾ and nonlinear χ⁽²⁾ susceptibilities. Thus, the observed anisotropy can only be related to χ⁽³⁾ effect, namely two-photon absorption, which leads to the photo-generation of free carriers that absorb the generated THz signal. Two-photon absorption in zinc-blende crystals is known to be due to a spin-orbit interaction between the valence and higher-conduction bands. We perform a couple of measurements that confirm our hypothesis, as well as we fit the recorded data with a simple model. This two-photon absorption effect makes difficult an efficient generation, through optical rectification in <?111 > zinc-blende crystals, of THz beams of any given polarization state by only monitoring the laser pump polarization.     

用飞秒激光制作高精度微光学器件的最新研究进展

文中介绍了飞秒激光与透明介质材料相互作用的多种机理和理论,重点综述了飞秒激光在制作波导、光栅及光存储结构等方面的最新研究进展和发展趋势.     

Decoding with Stretched Pulses in Laser PPM Communications

The design and performance of optical PPM communication systems with ideal (rectangular) pulses have been well documented. However, many optical channels (fibers, atmosphere, clouds) are extremely dispersive to narrow pulses, producing receiver pulses that are spread (stretched) in time. This stretching produces interslot interference within a PPM frame, and if severe enough, can stretch over several frames (intersymbol interference). In this paper, laser pulse stretching in optical PPM formats is investigated in terms of performance degradation and decoder design alternatives. Several methods are considered for combating the pulse stretching, including pulse equalization, extended pulse integration, and pulse shape matching. Performance of these methods is compared for the case of exponential stretching and Gaussian statistics.