Browsing by Author "Ji, Xiaoling"

Now showing 1 - 7 of 7

Citation Count: Eyyuboğlu, H.T., Ji, X. (2010). An analysis on radius of curvature aspects of hyperbolic and sinusoidal Gaussian beams. Applied Physisc B-Lasers And Optics, 101(1-2), 353-359. http://dx.doi.org/10.1007/s00340-010-4039-1
An analysis on radius of curvature aspects of hyperbolic and sinusoidal Gaussian beams
(Springer, 2010) Eyyuboğlu, Halil T.; Ji, Xiaoling; 7688
The effective radius of curvature of hyperbolic and sinusoidal Gaussian beams in free space and turbulent atmosphere is studied analytically and numerically. It is shown that the radius of curvature rises with growing source size, and changes slowly with wavelength. In general, given the same source and propagation settings, the beams can be listed in descending order of radius of curvature magnitudes as sinh Gaussian, cosh Gaussian, sine Gaussian, pure Gaussian and cos Gaussian beams. However, the radius of curvature and the difference of the radius of curvature between the different beams reduce with growing strength of turbulence because the beam's spatial phase distribution is destroyed by turbulence
Citation Count: Ji, X., Baykal, Y., Jia, X. (2013). Changes of the centroid position of laser beams propagating through an optical system in turbulent atmosphere. Optics and Laser Technology, 54, 199-207. http://dx.doi.org/10.1016/j.optlastec.2013.05.027
Changes of the centroid position of laser beams propagating through an optical system in turbulent atmosphere
(Elsevier Science Ltd, 2013) Ji, Xiaoling; Baykal, Yahya; Jia, Xinhong; 7812
In this paper, the effects of atmospheric turbulence, initial field amplitude, optical system and thermal blooming on the centroid position of laser beams propagating through the atmosphere are studied in detail. With the average over the ensemble of the turbulent medium, the centroid position is independent of turbulence. However, the centroid position depends on the centroid positions at the source plane and in the far-field, and the elements of ray-transfer-matrix. The physical reason why the centroid position changes on propagation is that the far-field centroid position is not located on the propagation z-axis due to the field phase distortion and the decentred intensity. The centroid position of laser beams with the spherical aberration and the decentred intensity is examined analytically. When laser beams with the decentred intensity propagate through the atmosphere, the effect of thermal blooming on the centroid position is investigated by using the four-dimensional (4D) computer code of the time-dependent propagation of high power laser beams through the atmosphere.
Citation Count: Baykal, Y., Cai, Y., Ji, X. (2012). Field correlations of annular beams in extremely strong turbulence. Optic Communications, 285(21-22), 4171-4174. http://dx.doi.org/10.1016/j.optcom.2012.07.006
Field correlations of annular beams in extremely strong turbulence
(Elsevier Science Bv, 2012) Baykal, Yahya; Cai, Yangjian; Ji, Xiaoling; 7812
The field correlations of annular beams are formulated when the atmosphere assumes extremely strong turbulence. Thicker and larger ring sized annular beams are found to exhibit larger absolute field correlations. For the same transverse distance at the receiver plane, annular beams attain larger field correlations if the transverse distance starts from the receiver origin. Comparisons of the annular beam absolute field correlations in extremely strong turbulence with the no turbulence results show that the absolute field correlation variations follow similar trends, except that the magnitudes of the absolute field correlations are much smaller in extremely strong turbulence and the annular fields become decorrelated at very short transverse distances. When the inner scale of turbulence becomes smaller, the absolute field correlations of the annular beams in extremely strong turbulence become smaller.
Citation Count: Eyyuboğlu, H.T., Ji, X. (2013). Radius of curvature of Bessel and modified Bessel Gaussian beams. Optic Communications, 298, 30-33. http://dx.doi.org/10.1016/j.optcom.2013.02.039
Radius of curvature of Bessel and modified Bessel Gaussian beams
(Elsevier Science Bv, 2013) Eyyuboğlu, Halil T.; Ji, Xiaoling; 7688
We analyze the radius of curvature of Bessel Gaussian (BG) and modified Bessel Gaussian (mBG) beams. The study is based on the results of analytic derivation as well as those of the random phase screen approach. Our results are displayed in graphs as variations of radius of curvature against propagation distance at various settings of beam order, width parameter, source focal length, wavelength, refractive index structure constant. Our findings indicate that mBG beams, in general will have larger radius of curvature values than BG beams. It is further observed that increases in beam order will lead to greater radius of curvatures. Rises in the width parameter will reveal more the differentiations between BG and mBG beams. At small focal lengths, the difference between BG and mBG beams is hardly noticeable. Higher wavelengths will initially cause a reduction in the radius of curvature, but at longer propagation distances, the reverse will happen. Increases in the refractive index structure constant will lead to smaller radius of curvature values. A general agreement is found in comparing the analytic results of BG beams with those of phase screen approach.
Citation Count: Baykal, Y., Luo, Y., Ji, X. (2016). Scintillations of higher order laser beams in anisotropic atmospheric turbulence. Applied Optics, 55(33), 9422-9426. http://dx.doi.org/10.1364/AO.55.009422
Scintillations of higher order laser beams in anisotropic atmospheric turbulence
(Optical Soc Amer, 2016) Baykal, Yahya; Luo, Yujuan; Ji, Xiaoling; 7812
The scintillation index of higher order laser beams is examined when such beams propagate in anisotropic atmospheric turbulence. Anisotropy is introduced through non-Kolmogorov atmospheric turbulence. The scintillation index results are obtained by employing the Rytov method solution; thus the results are valid for weak anisotropic atmospheric turbulence and for horizontal links. Variations in the scintillations are shown for various higher order laser modes against the changes in the optical source size, power law exponent of anisotropic non-Kolmogorov spectrum, anisotropic factors, and link length. Our results can be used in the design of optical wireless communication systems used between airplanes.
Citation Count: Li, X...et al. (2010). Turbulence distance of radial Gaussian Schell-model array beams. Applied Physisc B-Lasers And Optics, 98(2-3), 557-565. http://dx.doi.org/10.1007/s00340-009-3825-0
Turbulence distance of radial Gaussian Schell-model array beams
(Springer, 2010) Li, X.; Ji, Xiaoling; Eyyuboğlu, Halil T.; Baykal, Yahya; 7688; 7812
The effect of turbulence on the spreading of radial Gaussian Schell-model (GSM) array beams is studied quantitatively by examining the mean-squared beam width. The analytical expression for the turbulence distance z (T) of radial GSM array beams is derived by using the integral transform technique, which indicates within what ranges radial GSM array beams will be less affected by turbulence. It is shown that the effect of turbulence on the spreading of radial GSM array beams can be reduced by choosing the suitable array beam parameters and the type of the beam superposition. In addition, a comparison with the previous work is also made
Citation Count: Lu, L., Ji, X., Baykal;Y. (2014). Wave structure function and spatial coherence radius of plane and spherical waves propagating through oceanic turbulence. Optics Express, 22(22), 27112-27122. http://dx.doi.org/10.1364/OE.22.027112
Wave structure function and spatial coherence radius of plane and spherical waves propagating through oceanic turbulence
(Optical Soc Amer, 2014) Lu, Lu; Ji, Xiaoling; Baykal, Yahya; 7812
The analytical formulae for the wave structure functions (WSF) and the spatial coherence radius of plane and spherical waves propagating through oceanic turbulence are derived. It is found that the Kolmogorov five-thirds power law of WSF is also valid for oceanic turbulence in the inertial range. The changes of the WSF and the spatial coherence radius versus different parameters of oceanic turbulence are examined