共查询到20条相似文献,搜索用时 31 毫秒
1.
应用电子与多光子集团非线性Compton散射模型,将入射和散射光作为离子的传输机制,研究了Compton散射下多束相干强耦合激光等离子体中离子的运动,给出了相对论离子动力学方程,并进行了数值模拟。研究发现,散射使光的传播速度减小,系统的矢势和标势增大,由入射和散射光形成的多束相干强耦合激光能使质子加速到5.40GeV的能量,而耦合轴向电场在其中起着关键作用。 相似文献
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应用电子与多光子集团非线性Compton散射模型,将入射和散射光作为离子的传输机制,研究了Compton散射下多束相干强耦合激光等离子体中离子的运动,给出了相对论离子动力学方程,并进行了数值模拟。研究发现,散射使光的传播速度减小,系统的矢势和标势增大,由入射和散射光形成的多束相干强耦合激光能使质子加速到5.40GeV的能量,而耦合轴向电场在其中起着关键作用。 相似文献
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The hydrodynamic equations of superfluids for a weakly interacting Bose gas are generalized to include the effects of periodic optical potentials produced by stationary laser beams. The new equations are characterized by a renormalized interaction coupling constant and by an effective mass accounting for the inertia of the system along the laser direction. For large laser intensities the effective mass is directly related to the tunneling rate between two consecutive wells. The predictions for the frequencies of the collective modes of a condensate confined by a magnetic harmonic trap are discussed for both 1D and 2D optical lattices and compared with recent experimental data. 相似文献
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Design of optical coupling systems between two-dimensional quasi-stadium laser diodes and single-mode optical fibers 总被引:1,自引:0,他引:1
Optical coupling systems between a two-dimensional quasi-stadium laser diode and single-mode optical fibers using gradient-index
rod lenses are designed for both stable and unstable laser resonators for the first time. A novel numerical approach using
a combination of the extended Fox-Li calculation method and Gaussian beam transformations is proposed. In the case of a stable
laser resonator, two kinds of beam propagation modes appear, namely the axis mode, in which an optical beam propagates along
the cavity axis, and the ring mode, in which optical beams propagate along the diamond-shaped trajectory. The coupling efficiencies
are found to be 54% for the axis mode and 52% for the ring mode. In contrast, an unstable laser resonator exhibits complicated
modes, in which several highly directional beams are emitted from the end mirrors. The total coupling efficiency for these
output beams is calculated to be 9.6%. The 3-dB tolerances for the lens pitch and alignment angles of the gradient-index rod
lenses are also discussed. 相似文献
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Cold atom physics in space station arouses a lot of interest of scientists. We investigate the dynamical output process of the space continuous atom laser by solving nonlinear Gross-Pitaevksii equations numerically. Slow-moving continuous atom beams in two directions are observed simultaneously. The slow-moving coherent atom beams can be used as a source of atom interferometer to realize long-time measurements. We also control the output of space atom laser by adjusting the output coupling strength. 相似文献
7.
O. De Pascale C. Esposito M. Lepore P. Boffi M. Gaudio M. Vilnio 《Optics and Lasers in Engineering》1989,10(2)
Plane-polarized CO2 laser beams can be successfully employed in controlled surface temperature laser heat treating in order to improve the coupling between radiation and steel. The coupling efficiency has been quantitatively determined by means of a simple energy balance model, by using a medium-power CO2 laser. In this way, the angle at which the best coupling can be obtained has also been singled out. Moreover, some heat treatments performed with a high power laser beam obliquely impinging on medium carbon steel samples have confirmed that controlled surface temperature laser heat treating can be completely free of the problems concerning the use of coatings generally employed. 相似文献
8.
The absorption of a resonant coupling laser driving a closed degenerate two-level system in an atomic cesium beam was investigated as a function of the detuning of a second laser probing the same transition. The measurements were performed for four different polarization combinations of the two laser beams. Except for the beams of counterrotating polarizations all coupling-laser absorption profiles showed "absorption within transparency," i.e., the absorption in the region around the two-photon resonance was smaller than the absorption corresponding to the one-photon transition induced by the coupling laser, and an extra absorption peak was observed on this curve at the two-photon resonance. With regard to the beams of counterrotating polarizations we observed a switch from absorption within transparency to "transparency within transparency" when the probe-laser power exceeded the constant coupling-laser power. In other words, the cesium ensemble became mostly transparent to the coupling-laser beam at the two-photon resonance. 相似文献
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The design and operation of a novel optically pumped molecular gas laser cell, which uses geometrical coupling and is compatible with high energy unstable resonator CO2 laser pump beams, is described. The attainment of high energy output densities (>0.5J?1>-1) from the 12.08 μm and 12.81 μm NH3 laser transitions using this pumping arrangement is reported. 相似文献
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This Letter presents an investigation of the excitation of an upper hybrid wave (UHW) by cross focusing of two intense laser beams in a collisionless hot magnetoplasma, when relativistic and ponderomotive nonlinearities are operative. The electric vectors of the two beams are polarized along uniform static magnetic field and the beams propagate perpendicular to the static magnetic field. Analytical expressions for the beam width of the laser beams, electric vector and power of the excited UHW and energy gain have been obtained. The UHW generation at the difference frequency and particle acceleration has also been studied. The nonlinear coupling between intense laser beams and UHW is so strong that UHW gets excited and a large fraction of the laser beam energy gets transferred to UHW and this UHW accelerates electrons. It has been shown that the presence of a magnetic field affects significantly the power of the UHW and energy gain by the electron in the presence of the UHW. 相似文献
14.
单模与多模光纤耦合器的光束合波 总被引:2,自引:1,他引:1
现有的光纤耦合器在作为分波器使用时具有较低的插入损耗,在作为合波器时插入损耗较大,为实现低损耗合波目的,提出一种由单模与多模光纤共同构成的混合型光纤耦合器。利用耦合波方程理论分析其工作原理,计算机模拟其耦合过程。采用熔锥法制作工艺,完成单模与多模光纤耦合器的制作,实验结果与理论模拟相吻合;该器件单模到多模光纤的耦合效率、多模到多模光纤的耦合效率均在90%以上,实现了两路光束的功率合波。作为低插入损耗合波器件可广泛应用于光通信以及双包层光纤激光器抽运光的注入。 相似文献
15.
应用多光子非线性Compton散射模型,研究了固体温度变化对光声信号强度的影响。结果表明,在Compton散射光和入射光形成的耦合光强度和频率不变时,随固体温度的升高,光声信号强度非线性迅速增强;固体温度不变时,随耦合激光强度和频率的增大,光声信号强度几乎趋于0。 相似文献
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应用多光子非线性Compton散射模型,研究了固体温度变化对光声信号强度的影响。结果表明,在Compton散射光和入射光形成的耦合光强度和频率不变时,随固体温度的升高,光声信号强度非线性迅速增强;固体温度不变时,随耦合激光强度和频率的增大,光声信号强度几乎趋于0。 相似文献
17.
Several absorption and dispersion spectra of a probe and a coupling laser of different polarisations generating electromagnetically induced absorption in atomic caesium were measured and compared. In the case of at least one linearly polarised laser, electromagnetically induced absorption and absorption within transparency were observed for the probe and coupling laser, respectively. For laser beams of counter-rotating circular polarisation the coupling absorption spectra changed from absorption within transparency to transparency within transparency once the medium was saturated. However, the corresponding parametric dispersion spectra remained unchanged in structure. 相似文献
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Dependence of two-beam coupling gain and phase-shift of the signal beams on the frequency detuning for a coupled unidirectional ring resonators based on non-degenerate two-wave mixing in the photorefractive crystals have been investigated in details. The effects of various parameters characterizing the photorefractive medium such as frequency detuning, absorption strength, two-beam energy coupling strength and pump intensity of the external laser beams, on the two-beam coupling gain and phase-shift of the signal beams for a coupled UPRR have also been studied in details. It has been found that the photorefractive gain of the signal beam in the primary cavity of the coupled UPRR can be enhanced to the higher order by taking the lower value of the frequency detuning of the primary cavity which could exist at much lower value of the absorption strength of the crystal B. This higher value of photorefractive gains in the cavities are responsible for the strong coupling between the modes of the oscillations of the coupled UPRR. 相似文献
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为了稳定半导体激光器激射光束在光纤传输过程的耦合效率,提出一种沟槽结构的半导体激光器,并对该结构激光器的光束、耦合效率及P-I特性进行研究。在普通条形半导体激光器的脊形区刻蚀了周期性的沟槽结构,来改善半导体激光器有源区的增益分布。通过对比普通结构与沟槽结构半导体激光器的光束分析,测试其耦合效率以及P-I特性。结果表明:沟槽结构的半导体激光器能够使光腔内模式更加稳定,输出光束更加集中,并避免了"Kink"效应的发生;与此同时,耦合效率提高至97.7%,并且较普通结构激光器更为稳定。沟槽结构半导体激光器有效地解决了光斑跳动问题,稳定了激光器的耦和效率。 相似文献