长波长1.3μmInGaAsP／InP外腔主动锁模半导体激光器

利用外腔主动锁模技术,得到了9ps脉宽的1.3μm InGaAsP/InP半导体激光超短脉冲。在外腔中加入法珀标准具后,获得了可调谐变换极限的锁模脉冲。     

NAB对撞增强相位共轭腔快锁模特性

本文分析了NAB[NdAl_3(BO_3)_4]自激活激光晶体脉冲被动锁模的优越性。研究了对撞增强自起动自泵浦近简并四波混频相位共轭腔的形成条件及其在锁模过程中的作用。首次演示了NAB对撞增增强快速压缩脉冲锁模过程。获得了平均7ps的超短脉冲的实验结果。     

Mode-locking in nonlinear rotordynamics

Summary We present a computer-assisted study of the dynamics of two nonlinearly coupled driven oscillators with rotational symmetry which arise in rotordynamics (the nonlinearity coming from bearing clearance). The nonlinearity causes a splitting of the twofold degenerate natural frequency of the associated linear model, leading to three interacting frequencies in the system. Partial mode-locking then yields a biinfinite series of attracting invariant 2-tori carrying (quasi-) periodic motion.Due to the resonance nature, the (quasi-) periodic solutions become periodic in a corotating coordinate system. They can be viewed as entrainments of periodic solutions of the associated linear problem. One presumably infinite family is generated by (scaled) driving frequencies = 1+2/n,n = 1,2,3,...; another one is generated by frequencies =m,m = 4,5,6,... Both integersn andm can be related to discrete symmetry properties of the particular periodic solutions.Under a perturbation that breaks the rotational symmetry, more complicated behavior is possible. In particular, a second rational relation between the frequencies can be established, resulting in fully mode-locked periodic motion.     

基于主动锁模控制的激光谐波研究

介绍一种采用主动锁模控制产生超短激光脉冲序列的方法。首先通过基于主动锁模激光系统的参量自治微分方程思想,导出了系统出现稳定条件时参数设置方法。然后利用铌酸锂的非线性,展开成贝赛尔系数的函数级数,载频与边频数差为调制频率的整数倍,最后产生高重复频率超短光脉冲,得到高阶锁模脉冲,实验结果表明:其通过调节调制器的调制参数来控制谐振腔中的模式损耗,在调制频率为１ＧＨz量级的情况下,可获得重复频率１０ＧＨz的超短光脉冲序列,有啁啾时脉冲时域形状是很好的高斯型,没有出现明显畸变。     

Investigation of kerr-lens mode-locking of a flashlamp-pumped Nd:YAG laser

In this paper, we report that mode-locked operation is realized in a flashlamp-pumped Nd:YAG laser with a nearly critical stable resonator, using LiF:F₂⁻ color center crystal as a modulation device. A single pulse train with the energy of 25 mJ and the pulse duration of 82 ps is obtained. Both the theoretical and experimental results have shown that the mode-locked operation has resulted from kerr-lens effect formed in combination with self-focusing within Nd:YAG and an aperture at a specific point, but not directly from the saturable absorption of LiF:F₂⁻ crystal.     

Kerr Lens Mode-locked Operation of Yb:KYW Laser

Using a modified ABCD-matrix approach accounting for nonlinear refraction in active medium,the ranges of cavity parameters that provide a mode-locking of Yb∶KYW-laser in usual z-fold cavity configuration are determined.Taking the cavity parameters that provide a most efficient mode locking and based on fluctuation model,a numerical simulation of laser operation is performed.In the calculations the side-band pump power of 6W at 982 nm is used in 1 cm length KYW crystal with 1 cm×0.005 cm beam cross section.Calculations show that self-starting operation is possible with these parameters and dispersion compensation allows for bandwidth-limited ultrashort pulse generation.The shortest pulse duration was determined to be about 200 fs with self-starting buid-up time of 130 μs.Such a built-up time is comparable and even shorter than that one for the lasers with semiconductor saturable absorbers.The region of negative dispersion provided by prism pair for a stable ultrashort pulse generation was determined to be (-17000～-42000)fs2.     

Formation mechanism of bifurcation in mode-locked class-B laser

The random oscillations of many longitudinal modes are inevitable in both class –A and –B lasers due to their broadened atomic bandwidths. The destructive superposition of electric field components that are incoherently oscillating at the different longitudinal modes can be converted into a constructive one by using the mode-locking technique. Here, the Maxwell–Bloch equations of motion are solved for a three-mode class-B laser under the mode-locking conditions. The results indicate that the cavity oscillating modes are shifted by changing the laser pumping rate. On the other hand, the frequency components of cavity electric field simultaneously form the various bifurcations. These bifurcations satisfy the well-known mode-locking conditions as well. The atomic population inversion forms only one bifurcation, which is responsible for shaping the cavity electric field bifurcations.     

All-normal dispersion fiber lasers mode-locked with a nonlinear amplifying loop mirror

We review our recent progress on the design, modeling and construction of all-normal dispersion Yb-doped fiber lasers mode-locked using a nonlinear amplifying loop mirror. The all-fiber nature of the devices we consider permits accurate numerical simulations with minimal approximations or free-running parameters, and we describe in detail a refined numerical modeling scheme that combines generalized nonlinear envelope equations with analytically simulated gain dynamics. Guided by insights obtained from numerical modeling, we have experimentally realized robust, environmentally stable laser designs that offer flexible operation performance for a wide variety of applications. In particular, the unique all-PM-fiber design makes our devices ideally suitable for industrial laser micromachining applications.     

新型红外调Q、锁模用染料

合成了吸收波长为１４５５ｎｍ的红外域调Ｑ、锁模染料．它的碘乙烷、１，２－二氯乙烷及二甲基亚砜溶液对１３４０ｎｍ激光进行锁模时．显示优良性能．锁模脉宽为９０～１００ｐｓ。它的聚砜薄膜能对１０６４ｎｍ激光进行满意调Ｑ，脉宽为１０ｎｓ．     

Study of synchronously mode-locked and internally frequency-doubledcw dye laser

The analysis of the characteristics of a synchronously mode-locked and internally frequency-doubled dye laser is presented. Dependence of dye laser pulse characteristics on the cavity length mismatch of the pump laser and dye laser is studied. Variation of the minimum pulsewidth with intracavity bandwidth and the harmonic conversion efficiency is presented in the form of graphs.