Yanru Chen

Correlation between intensity fluctuations of light scattered from a quasi-homogeneous random media

The correlation between intensity fluctuations of light scattered from a quasi-homogeneous random media was analytically derived. We showed the correlation depends on spatial Fourier transforms of both the intensity and degree of spatial correlation of scattering potentials of the media, while the normalized correlation equals the squared modulus of the degree of spatial coherence of the scattered fields.

Changes of spectrum of light scattering on quasi-homogeneous random media

We study the spectrum of the field generated by beam radiated from quasi-homogeneous (QH) electromagnetic source scattering on QH media. Using the unified theory of coherence and polarization of random electromagnetic field, formulas for the spectral density and of the three dimensional scattered field for incidence of plane wave and a beam were derived respectively. From the spectral density of the scattered field, the normalized spectrum of the scattered field was obtained. It was found that the spectrum of the scattered field has a shift similar case of propagation.

Effect of astigmatism on states of polarization of aberrant stochastic electromagnetic beams in turbulent atmosphere

The effect of astigmatism on states of polarization of aberrant stochastic electromagnetic beams in turbulent atmosphere is investigated. Using the Gaussian-Schell model source with astigmatism, the analytical formula for the degree of polarization, the orientation angle, and the degree of polarization ellipse are derived. Analytical results show that different strengths of astigmatism have different effects on states of polarization on propagation. It is also shown that when the astigmatic coefficient of sources is large enough, states of polarization are hardly affected by atmospheric turbulence and the free-space diffraction phenomenon. The sufficient conditions for propagating with invariant polarization are derived and discussed.

Average Intensity and Spreading of Partially Coherent Four-Petal Gaussian Beams in Turbulent Atmosphere

The concept of partially coherent four-petal Gaussian (PCFPG) beam is introduced and described in analytical forms. Based on the Huygens-Fresnel integral formula, average intensity and beam spreading in turbulent atmosphere are derived in analytical expressions. Efiects of beam parameters and atmospheric structure constant on intensity distributions and efiective beam sizes are investigated in detail, respectively. Results show that PCFPG beams carrying larger coherence lengths or higher beam orders would be less afiected by turbulence. It is also indicated that, when the propagation distance increases, the PCFPG beam would convert into the Gauss- like proflle sooner or later, but this degradation can be reduced by modulating beam parameters. Results in this paper may provide potential applications in free-space optical communications.

Polarization Properties of Quasi-Homogeneous Beams Propagating in Oceanic Turbulence

Based on the extended Huygens-Fresnel principle and generalized Stokes theory, the evolution of polarization properties of beams generated by quasi-homogenous (QH) sources propagating in clear oceanic water was studied by the use of the oceanic turbulence spatial spectrum function. The results show that the beams have similar polarization self-reconstructed behavior under different turbulence conditions in the far field, but if the propagation distance is not long enough, the degree of polarization (DOP) fluctuates with much more complexity than state of polarization (SOP) of QH beams. The self-reconstructed ability of DOP at the special distance in turbulence would get to the best value if the values of coherence of width were chosen suitably, but for SOP, it has no best value.

Array of polarization singularities in interference of three waves

In this paper, we show that arrayed polarization singularities (PSs) can be generated by interference of three polarized waves. An experimental setup was proposed and used to produce one of the available types of array structures. We then analytically identified factors that control the structures of these arrays and classified all the structures into three types. Simulation results were used to assist this analysis.

Numerical generation of a polarization singularity array with modulated amplitude and phase

A point having no defined polarized ellipse azimuthal angle (circularly polarized) in a space-variant vector field is called a polarization singularity, and it has three types: Lemon, Monstar, and Star. Recently, the connection of polarization singularities has been performed. Inspired by this, we conduct a numerical generation of a polarization singularity array. Our method is based on two orthogonal linearly polarized light beams with modulated amplitude and phase. With appropriate distribution functions of amplitudes and phases we can control the polarized states of polarization singularities, which offer a possibility to simulate a polarization singularity array.

Far-field radiation of coherent and incoherent combined Lorentz- Gaussian laser array

Formulas for the radiated intensity distributions of coherent and incoherent combined Lorentz-Gaussian beam array are respectively derived by utilizing representations of the cross-spectral density of the far field. Intensity distributions versus azimuth angles are depicted by numerical examples. Effects of beam array numbers and separate distances etc. on far-field radiated profiles are shown and analyzed. Comparisons between the phenomenon respectively induced by coherent and incoherent combinations of Lorentz-Gaussian beams are also made and further discussed. These results may provide potential applications in producing high-power double heterojunction laser arrays.

Distributions of Amplitude and Phase Around C-points: Lemon, Mon-Star, and Star

The distributions of (or constraints for) amplitude and phase around C-points, including Lemon, Mon-Star and Star, are studied. A Cartesian coordinate system with origin at the C-point is established. Four curves, where the azimuthal angles of polarization ellipses are 0°, 45°, 90°, and 135° respectively, are used to determine the distributions. Discussions of these constraints illustrate why Mon-Star is rarer than Lemon or Star in experiments. The transformation relationships between these three polarization singularities (PSs) are also discussed. We construct suitable functions for amplitude and phase according to their constraints, and simulate several PSs of particular shapes. With the development of modulation techniques for amplitude and phase, it is clear that this work is helpful for generating arbitrarily shaped C-points in experiments.

Far-field vectorial structure of a higher-order cosh-Gaussian beam

Based on the vector angular spectrum representation and the method of stationary phase, the vectorial structural characteristics of a higher-order cosh-Gaussian (HOCG) beam in the far field are investigated. Analytical expressions for the energy flux distributions of the TE term, TM term and the whole beam are derived and illustrated by numerical examples. Influences of beam orders and cosh parameters on energy flux distributions are analyzed, respectively. Furthermore, the discrepancy for the total energy flux distributions between the non-paraxial and paraxial cases is presented and analytical explanations for the phenomenon are also given.