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91.
S. Kourtev N. Minkovski L. Canova O. Albert A. Jullien J. Etchepare S.M. Saltiel 《Optics Communications》2008,281(12):3375-3380
Novel χ(3)-based nonlinear polarization interferometer is theoretically and experimentally investigated. It enables efficient spatial and temporal filtering of femtosecond pulses via generation of cross-polarized wave. By changing the interferometer parameters different beam shapes can be obtained. 相似文献
92.
M.H. Mahdieh 《Optics Communications》2008,281(13):3395-3402
In this paper, propagation of a Gaussian laser beam through turbulent atmosphere is evaluated numerically. The beam quality factor for the propagated beam has been estimated for different turbulent conditions that are characterized by parameter Cn. The calculations show that the beam quality can be affected dramatically by atmospheric turbulence and the laser beam size and wavelength have major role in the results. Furthermore, the propagation of laser beam in longer distance results in more spatial perturbation of the beam. The results of these calculations and evaluation of beam quality factor M2 can be used for estimating the refractive index structure parameter (or atmosphere turbulent parameter) Cn. 相似文献
93.
Spreading of spatially partially coherent polychromatic beams in atmospheric turbulence 总被引:1,自引:0,他引:1
Taking the polychromatic Gaussian Schell-model (GSM) beam as a typical example of spatially partially coherent polychromatic beams, the spreading of polychromatic GSM beams in atmospheric turbulence is studied. The mean-squared width of polychromatic GSM beams in turbulence is derived by using the effective source and the strong fluctuation models. It is shown that the same result is obtained using both the models. The diffraction, atmospheric turbulence and beam polychroism result in a spreading of polychromatic GSM beams. If the scaling law fails, the spreading of polychromatic GSM beams increases with increasing bandwidth Γ, but the influence of Γ on the spreading of polychromatic GSM beams becomes small as the structure constant Cn2 of the refractive index and spatial correlation parameter α increase. The spreading of polychromatic GSM beams increases as Cn2 increases and α decreases. Spatially partially coherent polychromatic beams are less sensitive to the effects of atmospheric turbulence than spatially fully coherent polychromatic beams. 相似文献
94.
J. Zafar H. Zafar K. Masood A. A. P. Gibson 《International Journal of Infrared and Millimeter Waves》2008,29(12):1205-1214
High power line source emitter assembly was coupled to a twin symmetric H-plane slab loaded accelerating structure for beam
acceleration. Closed form field analysis of the accelerating structure that includes guideline information regarding modal
hierarchy, mode nomenclature, propagation plane, cut-off plane and dispersion relations is presented. Furthermore it was confirmed
that by using symmetrically loaded dielectric accelerating structures with one rotated through 90° results in exerting a uniform
acceleration impact on a travelling beam passing through the structure. 相似文献
95.
96.
We report the growth by Molecular Beam Epitaxy (MBE), fabrication and characterization of silicon doped 20 layer InAs dot in a well quantum dot infrared photo detector (DWELL-QDIP) device structures. Two structures with InAs dots of vertical heights of 50 Å and 40 Å were compared. A 2–8 μm band normal incidence photo response of the detector with polarization and bias dependence was obtained at 77 K. The specific peak detectivity D1 be 0.8 × 109 Jones for one of the detectors. 相似文献
97.
The aim of this paper is to develop a reduction method to determine the modal characteristics of viscoelastic sandwich structures. The method is based on the high order Newton algorithm and reduction techniques. Numerical tests have been performed in the case of sandwich beams and cylindrical shells. The comparison of the results obtained by the reduction method with those given by direct simulation shows both a good agreement and a significant reduction in computational cost. 相似文献
98.
Consider an elastic thin three-dimensional body made of a periodic distribution of elastic inclusions. When both the thickness of the beam and the size of the heterogeneities tend simultaneously to zero the authors obtain three different one-dimensional models of beam depending upon the limit of the ratio of these two small parameters. 相似文献
99.
《Physics letters. A》2020,384(2):126046
Discussed is the dynamics of optical vortices carrying multi-topological charges, which are nested in optical envelopes with non-circular symmetric amplitudes and phases. As a result of the non-circular symmetry either in amplitudes or in phases, the vortices can split in pairs from the centers of the host beams. During the splitting process of every constituent vortex, its carried integer charges evolve into fractional ones. Furthermore, the overall rotations of the host optical envelopes are found to happen in the splitting process. The theoretical results may find potential applications in beam shaping and engineering. 相似文献
100.
We report a beam-delivery system consisting of a non-digitized diffractive beam splitter and a Fourier transform lens. The system is applied to the deep-drilling of silicon using a nanosecond pulse laser in the manufacture of inkjet printer heads. In this process, a circularly polarized pulse beam is divided into an array of uniform beams, which are then delivered precisely to the process points. To meet these requirements, the splitter was designed to be polarization-independent with an efficiency>95%. The optical elements were assembled so as to allow the fine tuning of the effective overall focal length by adjusting the wavefront curvature of the beam. Using the system, a beam alignment accuracy of<5 μm was achieved for a 12-mm-wide beam array and the throughput was substantially improved (10,000 points on a silicon wafer drilled in ~1 min). This beam-delivery scheme works for a variety of laser applications that require parallel processing. 相似文献