共查询到20条相似文献,搜索用时 31 毫秒
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G. S. Gevorgyan R. B. Alaverdyan R. S. Hakobyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2011,46(4):156-159
Nonlinear optical orientational phenomena induced by laser in BAAB 1005-type nematic liquid crystals are studied experimentally.
It is shown that these phenomena in the field of a single-mode laser field are displayed stronger, if the liquid crystal material
is pre-irradiated with certain-frequency visible radiation. These phenomena are caused by the trans-cis transition in molecules
of azobenzene liquid crystal BAAB 1005 at absorption of certain frequency radiation. Qualitative explanation of the experimental
results is based on the simultaneous action of several mechanisms including thermomechanical. 相似文献
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Experimental studies of gain lineshapes in an optically pumped Na2 dimer laser system are reported. All the phenomena predicted by the three level model are observed and gain in four-level systems induced by collision is demonstrated experimentally. 相似文献
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Laser-diode pumped Q-switched ytterbium-doped switching time of acousto-optic modulator (AOM) fiber laser is studied experimentally by controlling the The characteristics of Q-switched pulses with different rise time of AOM regulated by the laser beam size along the window of AOM are presented. Meanwhile, the behaviors of Q-switched pulses are achieved by regulating the switching time of AOM. The singlerepetition-rate and half-repetition-rate phenomena are described and discussed. The experimental results confirm that the fiber laser with lower level inversion population can be more easily operated for half- repetition-rate generation. 相似文献
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S. O. Konorov A. A. Ivanov D. A. Akimov A. V. Yakimanskii M. V. Alfimov A. M. Zheltikov 《JETP Letters》2004,80(3):167-171
Third-harmonic and sum-frequency generation in quadratically nonlinear azopolymer films is experimentally studied using femtosecond chromium forsterite laser pulses. A noncollinear geometry of sum-frequency and third-harmonic generation developed and implemented in this work allows the influence of the time ordering of ultrashort laser pump pulses on nonlinear-optical phenomena to be experimentally observed. Femtosecond laser pulses induce transitions of azopolymer molecules to an electronically excited state and produce vibrational wave packets, leading to an asymmetry in the dependence of the efficiency of second-and third-order nonlinear-optical processes on the delay time between the pump pulses. 相似文献
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Wünsche HJ Bauer S Kreissl J Ushakov O Korneyev N Henneberger F Wille E Erzgräber H Peil M Elsässer W Fischer I 《Physical review letters》2005,94(16):163901
Two delay-coupled semiconductor lasers are studied in the regime where the coupling delay is comparable to the time scales of the internal laser oscillations. Detuning the optical frequency between the two lasers, novel delay-induced scenarios leading from optical frequency locking to successive states of periodic intensity pulsations are observed. We demonstrate and analyze these dynamical phenomena experimentally using two distinct laser configurations. A theoretical treatment reveals the universal character of our findings for delay-coupled systems. 相似文献
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《中国光学快报(英文版)》2015,(7)
The periodic ripple structures on wolfram and titanium surfaces are induced experimentally by linear polarized femtosecond laser pulses at small incident angles. The structural features show a material difference in the s- and p-polarized laser irradiation. The interspace between the ripples increases significantly for p-polarized laser irradiation when it exceeds a threshold angle, and the ripples' periodicities are larger than the wavelength of the incident p-polarized femtosecond laser; however, no significant change in the period of the ripples is observed with increasing incident angle for s-polarized laser irradiation. To explain these phenomena we propose a resonant absorption mechanism, by which the experimental observations can be interpreted. 相似文献
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The laser-induced metal and polymer melt jets are studied experimentally. Two classes of physical phenomena of interest are: first, the process of explosive phase change of laser induced surface ablation and second, the hydrodynamic jetting of liquid melts ejected from a beamed spot. We focus on the dynamic link between these two distinct physical phenomena in a framework of forming and patterning of metallic and polymer jets using a high-power Nd:YAG laser. The microexplosion of ablative spot on a target first forms a pocket of hot liquid melt and then it is followed by a sudden volume change of gas-liquid mixture leading to a pressure-induced spray jet ejection into surrounding medium. 相似文献
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采用基于Guo,Aberg和Crasemann发展的强激光场中的非微扰量子散射理论(GAC理论),研究了线偏振双色激光场中氪(Kr)原子阈上电离的光电子角分布,双色激光场由一系列相同的单周期激光脉冲组成.研究发现光电子角分布有强烈的位相依赖关系,且呈现出反演不对称性、喷射结构和展宽结构等现象,这为实验上通过改变双色激光场的相对相位来观察和控制光电子角分布提供了一种有效的方法. 相似文献
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Da-he Liu Jin-wei Shi Xu-dong Chen Min Ouyang Wen-ping Gong 《Frontiers of Physics in China》2010,5(1):82-106
The principle of a lidar based on Brillouin scattering is introduced. The basic physics of the Brillouin lidar is discussed.
The applications of the Brillouin lidar in remote sensing of the ocean, such as measurement of the sound speed and the bulk
viscosity of water and detecting submerged objects are investigated. An actual Brillouin lidar system is developed. Also,
several basic problems related to Brillouin lidar are studied in detail. The attenuation coefficient of a pulsed laser beam
with high pulsed energy in water is investigated; it is helpful to reveal the propagation property of a laser beam in water.
The investigations on the threshold value of SBS are made theoretically and experimentally. Finally, a novel phenomena is
investigated experimentally, in which Stimulated Raman scattering can be enhanced by stimulated Brillouin scattering. 相似文献
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利用氧化石墨烯作为可饱和吸收体,在被动锁模全正常色散掺镱光纤激光器中研究了多脉冲的现象,在同一抽运功率不同偏振态下,实验获得了矩形脉冲谐波锁模、耗散孤子谐波锁模、准谐波锁模,脉冲峰值周期性调制,脉冲簇、脉冲束、混沌多重脉冲的多脉冲现象,插入激光腔内的2nm窄带滤波器具有限制增益带宽、对脉冲塑形、诱导多脉冲产生的作用,调节偏振控制器相当于改变腔内增益,是实现不同类型多脉冲现象的主要原因,本实验研究有利于加深对多脉冲动力学行为在正常色散区域氧化石墨烯锁模掺镱光纤激光器中的理解。 相似文献
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Experimental measurements of power spectra of a single longitudinal and transverse mode ring dye laser are presented that reveal the critical slowing down of the laser near threshold. External pump noise serves as a probe of the frequency response of the dye laser. Detailed comparisons of the spectral characteristics with computer simulations and an approximate analytic theory are given. The dynamics of spatial pattern formation in a multimode dye laser is examined through measurements of first-passage-time distributions. A comparison of the experiments with computer simulations based on a simple theoretical model of the two-mode laser shows qualitative agreement. These measurements indicate that there are a variety of complex phenomena associated with the transverse mode pattern formation dynamics that need to be addressed theoretically and studied further experimentally. 相似文献
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对横向效应导致单纵模多横模CO_2激光器失稳进行了实验研究.观测到了经各种途径到达的激光混沌态,并对其物理机制进行了探讨. 相似文献
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Carrier-envelope phase effects on high-harmonic generation driven by mid-infrared laser field
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The influence of the carrier-envelope phase on high-harmonic generation is investigated, both experimentally and theoretically, for three different interaction gas media, driven by mid-infrared, few-cycle and CEP-stabiUzed laser pulses. Different patterns of harmonic spectra with varying CEP for the three interaction gas media are observed. Furthermore, in comparing our experiment results to the previous works driven by near-infrared laser pulses, different phenomena are found. Through numerical simulation, we find that for the two different kinds of driving fields, i.e. mid-infrared and near-infrared laser pulses, different kinds of electron trajectories contribute to the generation of high harmonics. 相似文献
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Cr^4+:YAG调Q特性的理论和实验研究 总被引:22,自引:1,他引:21
从理论和实验两个方面研究Cr^4+:YAG的调Q特性,测量了Cr^4+:YAG调QNd^3+:YAG激光器在不同条件下脉冲能量和脉冲宽度,并与理论结果进行比较,结果显示脉冲能量的理论结果与实验结果能较发地符合,脉冲工的理论结果与实验结果变化趋势大致相一致,文中还对Cr^4+:YAG调QNd^3+:YAG激光器的其它实验现象给出定性解释。 相似文献
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J.C. Conde P. González F. Lusquiños S. Chiussi J. Serra B. León 《Applied Physics A: Materials Science & Processing》2007,88(4):667-671
Changes in target surface morphology and ablation plume direction have been experimentally observed during the initial stages
of the silicon laser ablation process. A relationship between both phenomena can be observed upon analysing the temperature
field induced by the laser beam in a rough surface material. Theoretical studies on the deflection of the ablation plume are
presented. These analyses are based on the hypothesis that particles that reach evaporation temperature will exit normally
to the target surface with a velocity that is proportional to the surface temperature and the amount of the ablated material.
Numerical solutions and experimental results of laser ablation process of silicon targets are found to agree with theoretical
studies.
PACS 42.25.Lc; 79.20.Dc; 02.70.Dc 相似文献