Browsing by Author "Cai, Y."

Now showing 1 - 7 of 7

Citation Count: Çil, Celal Zaim...et al (2010). "Beam wander of J (0)- and I (0)-Bessel Gaussian beams propagating in turbulent atmosphere", Applied Physics B-Lasers and Optics, Vol. 98, No. 1, pp. 195-202.
Beam wander of J (0)- and I (0)-Bessel Gaussian beams propagating in turbulent atmosphere
(2010) Çil, Celal Zaim; Eyyüboğlu, Halil Tanyer; Baykal, Yahya Kemal; Korotkova, O.; Cai, Y.; 7812
Root mean square (rms) beam wander of J (0)-Bessel Gaussian and I (0)-Bessel Gaussian beams, normalized by the rms beam wander of the fundamental Gaussian beam, is evaluated in atmospheric turbulence. Our formulation is based on the first and the second statistical moments obtained from the Rytov series. It is found that after propagating in atmospheric turbulence, the collimated J (0)-Bessel Gaussian and the I (0)-Bessel Gaussian beams have smaller rms beam wander than that of the Gaussian beam, regardless of the choice of Bessel width parameter. However, the extent of such an advantage depends on the chosen width parameter, Gaussian source size, propagation distance and the wavelength. Focusing at finite distances of the considered beams causes the rms beam wander to decrease sharply at the propagation distances equal to the focusing parameter.
Citation Count: Çil, Ç.Z.;...et.al. (2010). "Beam wander of J 0- and i 0-Bessel Gaussian beams propagating in turbulent atmosphere", Applied Physics B: Lasers and Optics, Vol.98, No.1, pp.195-202.
Beam wander of J 0- and i 0-Bessel Gaussian beams propagating in turbulent atmosphere
(2010) Çil, C.Z.; Eyyuboğlu, H.T.; Baykal, Y.; Korotkova, O.; Cai, Y.; 7812
Root mean square (rms) beam wander of J 0-Bessel Gaussian and I 0-Bessel Gaussian beams, normalized by the rms beam wander of the fundamental Gaussian beam, is evaluated in atmospheric turbulence. Our formulation is based on the first and the second statistical moments obtained from the Rytov series. It is found that after propagating in atmospheric turbulence, the collimated J 0-Bessel Gaussian and the I 0-Bessel Gaussian beams have smaller rms beam wander than that of the Gaussian beam, regardless of the choice of Bessel width parameter. However, the extent of such an advantage depends on the chosen width parameter, Gaussian source size, propagation distance and the wavelength. Focusing at finite distances of the considered beams causes the rms beam wander to decrease sharply at the propagation distances equal to the focusing parameter.
Citation Count: Wang, F...et al. (2011). Partially coherent elegant Hermite-Gaussian beam in turbulent atmosphere. Applied Physisc B-Lasers And Optics, 103(2), 461-469. http://dx.doi.org/10.1007/s00340-010-4219-z
Partially coherent elegant Hermite-Gaussian beam in turbulent atmosphere
(Springer, 2011) Wang, F.; Cai, Y.; Eyyuboğlu, Halil T.; Baykal, Yahya; 7688; 7812
Based on the extended Huygens-Fresnel integral, analytical formulas for the cross-spectral density, mean-squared beam width and angular spread of a partially coherent elegant Hermite-Gaussian (HG) beam in turbulent atmosphere are derived. The evolution properties of the average intensity, spreading and directionality of a partially coherent elegant HG beam in turbulent atmosphere are studied numerically. It is found that the partially coherent elegant HG beam with smaller initial coherence width, larger beam order and longer wavelength is less affected by the atmospheric turbulence. Compared to the partially coherent standard HG beam, the partially coherent elegant HG beam is less affected by turbulence under the same condition. Furthermore, it is found that there exist equivalent partially coherent standard and elegant HG beams, equivalent fully coherent standard and elegant HG beams, and an equivalent Gaussian-Schell-model beam may have the same directionality as a fully coherent Gaussian beam whether in free space or in turbulent atmosphere. Our results can be utilized in short and long atmospheric optical communication systems
Citation Count: Cai, Y...et al. (2007). Propagation of laser array beams in a turbulent atmosphere. Applied Physisc B-Lasers And Optics, 88(3), 467-475. http://dx.doi.org/10.1007/s00340-007-2680-0
Propagation of laser array beams in a turbulent atmosphere
(Springer, 2007) Cai, Y.; Chen, Y.; Eyyuboğlu, Halil T.; Baykal, Yahya; 7688; 7812
The propagation of phase-locked and non-phase-locked laser array beams of radial and rectangular symmetries in a turbulent atmosphere are investigated based on the extended Huygens-Fresnel integral. The beamlet used in our paper for constructing the laser array beams is of elliptical Gaussian mode. Analytical formulae for the average irradiance of phase-locked and non-phase-locked radial and rectangular laser array beams are derived through vector integration and tensor operation. The irradiance properties of these laser array beams in a turbulent atmosphere are studied numerically. It is found that both phase-locked and non-phase-locked radial and rectangular laser array beams eventually become circular Gaussian beams in a turbulent atmosphere, which is much different from their propagation properties in free space. The propagation properties are closely related to the parameters of laser array beams and the structure constant of the turbulent atmosphere.
Citation Count: Eyyuboğlu, Halil Tanyer; Baykal, Yahya, "Propagation of partially coherent beams after a source plane ring aperture", Piers 2008 Hangzhou: Progress In Electromagnetics Research Symposium, Vols I And II, Proceedings, (2008).
Propagation of partially coherent beams after a source plane ring aperture
(Electromagnetics Acad, 2008) Eyyuboğlu, Halil T.; Baykal, Yahya; Cai, Y.; 7688; 7812
The propagation properties of partially coherent beams passing through a source placed ring aperture are examined. The derivation is based on the lowest order general beam formulation, such that our results are applicable to a wide range of beam. In this study, our focus is on fundamental Gaussian, cosh-Gaussian, cos-Gaussian, sinh-Gaussian, sine-Gaussian and annular beams. The aperture consists of inner and outer parts, thus the middle hollow part appears in the form of a ring. The propagation environment is turbulent. From the graphical outputs of the beams investigated, it is seen that despite the existence of the circular ring, during propagation, the beams tend to retain the basic profiles similar to the case of no aperture, but depending on the inner and outer radius dimensions, the propagated beams are reduced in intensity levels and become more spread. It is further observed that, when the inner part of the aperture has nonzero radius, ring formations are developed at the outer edges of the receiver plane intensities.
Citation Count: Eyyuboğlu, H.T., Baykal, Y. (2010). Scintillation calculations for partially coherent general beams via extended Huygens-Fresnel integral and self-designed Matlab function. Applied Physisc B-Lasers And Optics, 100(3), 597-609. http://dx.doi.org/ 10.1007/s00340-010-4125-4
Scintillation calculations for partially coherent general beams via extended Huygens-Fresnel integral and self-designed Matlab function
(Springer, 2010) Eyyuboğlu, Halil T.; Baykal, Yahya; Cai, Y.; 7688; 7812
We present scintillation calculations in weak atmospheric turbulence for partially coherent general beams based on the extended Huygens-Fresnel integral and a Matlab function designed to handle expressions both of the average intensity and the average squared intensity. This way, the integrations are performed in a semi-analytic manner by the associated Matlab function, and this avoids lengthy, time-consuming and error prone hand derivations. The results are obtained for the partially coherent fundamental and higher-order sinusoidal and annular Gaussian beams. By plotting the scintillation index against the propagation distance and source size, we illustrate the on-axis scintillation behaviors of these beams. Accordingly, it is found that within specific source and parameter ranges, partially coherent fundamental, higher-order sinusoidal and annular Gaussian beams are capable of offering less scintillations, in comparison to the fundamental Gaussian beam
Citation Count: Baykal, Yahya; Eyyuboğlu, Halil Tanyer, Cai, Y., "Scintillations in weak turbulence of annular beams whose individual components are incoherent", Piers 2010 Xi'an: Progress İn Electromagnetics Research Symposium Proceedings, Vols 1 And 2, (2010).
Scintillations in weak turbulence of annular beams whose individual components are incoherent
(Electromagnetics Acad, 2010) Baykal, Yahya; Eyyuboğlu, Halil T.; Cai, Y.; 7812; 7688
The scintillation index, arising from the intensity fluctuations in weak atmospheric turbulence of annular beams whose individual components are incoherent, is formulated. For such beams whose annularities are obtained by varying the source sizes and magnitudes of the individual beams, evaluations show that at very small sized beam structures, thinner beams possess smaller scintillations. As the sizes increase, the scintillation index values of thick and thin beams approach each other, eventually exhibiting the same scintillation behavior at large sized beam structures. Examination of the intensity fluctuations of the annular beams, whose individual incoherent components are at the same size but at different magnitudes, yield reverse behavior such that at very small sized beam structures, thicker beams possess smaller scintillations, however the scintillation values are very close to each other. Again, for large sized beams, the scintillation index values of thick and thin beams approach each other, eventually exhibiting the same scintillation behavior at large sized beam structures. Comparing the scintillation indices of annular beams whose individual components are incoherent to those of traditional annular beams of coherent components, it seems that for large sized beams, incoherently subtracted beams are advantageous, however the reverse is valid for very small sized beam structures.