环形腔被动锁模掺饵光纤激光器

通过在非线性偏振旋转环形腔内引入一种可旋转的在线起偏器,在保证装置的全光纤化结构的前提下,简化了被动锁模光纤激光器的结构.通过联合调节可旋转的在线起偏器、1/2波片和1/4波片的角度实现了掺饵光纤锁模脉冲20nm间隔的双波长调谐输出,调谐过程中观察到了锁模脉冲双波长状态.另外,从装置中去掉1/2波片后,仅调谐可旋转的在线起偏器和1/4波片也能够实现锁模脉冲的单波长稳定输出.     

36 W侧面抽运腔内倍频Nd:YAG/KTP连续绿光激光器

通过优化平-凹-平三镜折叠腔结构设计,利用大功率半导体激光器侧面抽运、Ⅱ类相位匹配KTP晶体腔内倍频,获得高效高功率连续绿色激光输出.当抽运电流约为36 A时,得到最高36.6 W的连续绿光激光输出,对应的光—光转换效率为8.71％.在输出功率33 W时测量激光功率稳定性,其功率不稳定度为0.27%.用刀口法测量了激光器高输出功率时的光束质量,光束质量因子小于8.对高功率抽运情况下三镜折叠腔的像散补偿、失调灵敏度和基模在腔内分布情况做了数值模拟. 关键词： 侧面抽运 腔内倍频 连续波     

Generation and characterization of NiO nanoparticles by continuous wave fiber laser ablation in liquid

Pulsed laser ablation in liquid (PLAL) has been widely applied for the generation of nanoparticles (NPs). We report on the generation of NiO NPs using a high-power, high-brightness continuous wave (CW) fiber laser source at a wavelength of 1,070 nm. Characterization of such NPs in terms of size distribution, shape, chemical composition, and phase structure was carried out by transmission electron microscopy (TEM), high-resolution TEM equipped with energy-dispersive X-ray (EDX), and X-ray diffraction (XRD). The results revealed the formation of NiO NPs in water with an average size of 12.6 nm. The addition of anionic surfactant sodium dodecyl sulfate (SDS) reduced the size of NiO NPs down to 10.4 nm. The shape of the NPs was also affected by the SDS, showing the change of shapes from spherical domination in water to tetragonal with increased SDS concentrations. Furthermore, the NiO NPs generated in water and SDS solutions were dual phase containing both cubic and rhombohedral structures. It was also found that the NiO NPs were single crystalline in nature irrespective of the size and shape.     

Optimization of the operational parameters in a fast axial flow CW CO2 laser using artificial neural networks and genetic algorithms

This paper presents an artificial intelligence approach for optimization of the operational parameters such as gas pressure ratio and discharge current in a fast-axial-flow CW CO₂ laser by coupling artificial neural networks and genetic algorithm. First, a series of experiments were used as the learning data for artificial neural networks. The best-trained network was connected to genetic algorithm as a fitness function to find the optimum parameters. After the optimization, the calculated laser power increases by 33% and the measured value increases by 21% in an experiment as compared to a non-optimized case.     

Theory of passively mode-locked lasers with self-frequency shift and saturable absorber response

A general theoretical model for passively mode-locked lasers is presented, in which both the self-frequency shift and either a fast or a slow saturable absorber response are taken into account. An exact soliton-like solution and condition for its existence are obtained under a definite compatible condition. The stability of the solution is analyzed by using a variational method, and a parameter region, in which the solution is linearly stable, is acquired theoretically. To verify the theoretical predictions, a typical example is given for stable pulse propagation over a long distance. The numerical results show that the soliton-like solution is stable under some perturbations within the linearly stable region and an arbitrary Gaussian pulse converges to the exact soliton-like solution after evolution in a distance.     

对撞锁模染料激光器中锁模脉冲列的耦合效应

论述了在对撞锁模染料激光器中必然存在锁模脉冲列耦合效应,此效应使输出脉冲较宽,且脉宽不稳定。用适当加厚锁模染料层等办法减弱该效应会使脉冲变窄且脉宽稳定。     

被动锁模激光器运转的先决条件

定量地导出了被动锁模激光器动转的先决条件，它们是泵浦速率的上退和激光介质饱和强度的下限。     

矿井下连续波激光点燃瓦斯的研究

根据激光破岩产生的温度分布和热爆炸的经典理论,推导出井下气体的点火温度与激光功率和瓦斯浓度的关系.在几种岩石和不同瓦斯浓度下进行了数值计算.给出矿井下应用连续波激光的功率阈值.     

Submillisecond detection of single rhodamine molecules in water

Using a modified confocal fluorescence microscope and a CW argon laser, we have measured fluorescence bursts from diffusing single Rh6G molecules that clearly exceed the background intensity. The exact average number of molecules in the observable volume elements was measured directly via the fluorescence intensity autocorrelation function. This allowed us to estimate the probability of finding several molecules simultaneously in the volume element. A tradeoff between the number of detected fluorescence photons and the signal-to-background ratio was observed. In a volume element of 0.24 fl, 4 photoelectrons on average were detected from a molecule of Rh6G with a fluorescence-to-background ratio of 1000, while the volume element of 60 fl yielded on average 100 photoelectrons with a background of 25 counts. In fast single-molecule detection the intersystem crossing into the triplet state plays an important role, affecting the maximum emission rate from the molecule.This is a peer-reviewed conference proceeding article from the Third Conference on Methods and Applications of Fluorescence Spectroscopy, Prague, Czech Republic, October 18–21, 1993.