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We introduce a partially coherent beam, called a multi-hyperbolic sine-correlated (MHSC) beam, by employing a multi-hyperbolic sine function to modulate the spectral degree of coherence. Based on the extended Huygens–Fresnel principle and second-order moments of the Wigner distribution function, we derive the analytical expressions for the spectral intensity, the root-mean-square (rms) angular width and the M 2 factor in turbulent atmosphere. Numerical results show that the intensity profile, which keeps the dark-hollow invariant in free space, will be gradually destroyed by the turbulence along the propagation distance. We believe that the MHSC beams have significant advantage over the hyperbolic sine-correlated beams for reducing the turbulence-induced degradation, especially for the MHSC beams with a higher beam order N . The effects of the beams parameters and the turbulent atmosphere on the beam quality are analyzed in detail.

International audience; We propose a method to generate beams according to transmission limitation condition by using the multi-distance phase retrieval algorithm. Propagation properties of hollow beams were determined by several intensity patterns along the travel axis. Predicted beams were obtained using a two-step phase filtering from a Gaussian beam with fundamental mode. An iterative phase retrieval method was employed for calculating the phase distribution in the filtering mask. This beam generation approach matched special propagation characteristics of the beams in practical applications.

We introduce a class of planar random source generating ring-shaped array profiles in the far field. The model for spatial correlation function of this new source is composed by the Fourier transform of the Laguerre-Gaussian array function with circular symmetry. The analytical expressions for the spectral density (average intensity) in free space and atmospheric turbulence are derived. The effect of the source parameters on the propagation properties are investigated in detail. Numerical results show that the source can produce a ring-shaped optical array profile consisting of dark-hollow-shaped or Gaussian-like-shaped beamlets at some distance, and then keep shape-invariant for long distances in free space. The number of rings, the position of beamlets, and other features can be conveniently controlled by changing the initial source parameters. In addition, increasing the relative separation distance of each beamlet or decreasing the radius of beamlets can reduce the turbulence-induced degradation.

By utilizing the extended Huygens-Fresnel principle, we derive the analytical formulas for the cross-spectral density matrix elements of a radially polarized multi-Gaussian Schell-model (RPMGSM) beam propagating in oceanic turbulence. Effects of beam parameters and oceanic turbulence parameters on the propagation properties of RPMGSM beams are investigated in detail by numerical simulation. Our results show that the RPMGSM beam with larger beam order M has an advantage over the radially polarized Gaussian Schell-model beam for reducing turbulence-induced degradation. Compared with temperature-induced turbulence fluctuation, the salinity-induced turbulence fluctuation makes a greater contribution to the influence on propagation properties of RPMGSM beams.

We propose an experimentally feasible scheme to produce bright four-color continuous-variable entanglement by intracavity quasi-phase-matching cascaded nonlinear optical frequency conversion in only one optical superlattice. The second, third and fourth harmonics can be generated by frequency doubling of the input fundamental field at frequency , the sum frequency of fundamental and second harmonic fields, and frequency doubling of the second harmonic field, respectively. The entanglement properties influenced by system parameters are theoretically discussed according to the sufficient inseparability criterion proposed by van Loock and Furusawa. Such compact multipartite continuous-variable entanglement has potential applications in quantum communication and computation networks.

We derive several analytical expressions for the root-mean-square (rms) angular width and the M(2)-factor of the multi-sinc Schell-model (MSSM) beams propagating in non-Kolmogorov turbulence with the extended Huygens-Fresnel principle and the second-order moments of the Wigner distribution function. Numerical results show that a MSSM beam with dark-hollow far fields in free space has advantage over the one with flat-topped or multi-rings far fields for reducing the turbulence-induced degradation, which will become more obvious with larger dark-hollow size. Beam quality of MSSM beams can be further improved with longer wavelength and larger beam width, or under the condition of weaker turbulence. We also demonstrate that the non-Kolmogorov turbulence has significantly less effect on the MSSM beams than the Gaussian Schell-model beam.

We introduce a new kind of partially coherent beam, non-uniformly Hermite–Gaussian correlated beam, by employing a non-uniformly Hermite function to modulate the spectral degree of coherence. The evolution of such scalar beam on propagation in free space and turbulent atmosphere are investigated. It is demonstrated that the spectral intensity distributions exhibit extraordinary propagation characteristics, such as self-focusing and laterally shifted intensity maxima. The position of the maximum intensity and the intensity profile can be controlled by the order of the Hermite function. The results can be useful in free-space optical communications and beam shaping.