Muchun Zhou

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.

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.

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.

VECTORIAL STRUCTURE OF A PHASE-FLIPPED GAUSS BEAM IN THE FAR FIELD

Based on the vectorial angular spectrum representation and the method of stationary phase, internal vectorial structures of a phase-∞ipped Gauss (PFG) beam difiracting in the far fleld are derived in analytical forms. The energy ∞ux for the TE term, TM term and the whole beam are derived and depicted by numerical examples. In∞uences of the f parameter on the whole energy ∞ux distributions are analyzed. Discrepancies of the whole energy ∞ux distributions between the paraxial and non-paraxial cases are shown in detailed manners. Furthermore, in∞uences of the f parameter on discrepancies between two cases are also studied.

Propagation properties of a partially coherent radially polarized beam in atmospheric turbulence

Abstract Based on the extended Huygens–Fresnel integral, second-order moments of the Wigner distribution function of a partially coherent radially polarized beam propagating through atmospheric turbulence are derived. Besides, propagation properties such as the mean-squared beam width, angular width, effective radius of curvature, beam propagation factor and Rayleigh range can also be obtained and calculated numerically. It is shown that the propagation properties are dependent on the spatial correlation length, refraction index structure constant and propagation distance.

Simulation of generation and dynamics of polarization singularities with circular Airy beams

The generation and dynamics of polarization singularities have been underresearched for years, while the focusing property of the topological configuration has not been explored much. In this paper, we simulated the generation of low-order polarization singularities with a circular Airy beam and explored the focusing property of the synthetic light field during propagation due to the autofocusing of the component. Our work researched the focusing properties of the polarization singularity configuration, which may help to develop its application prospect.

Condition for far-zone spectral isotropy of light transmitted from Young’s pinholes scattering on a quasi-homogeneous medium

The far-zone spectral isotropy of light transmitted from Youngs pinholes on scattering from a quasi-homogeneous medium has been discussed. A sufficient condition for the far-zone spectral isotropy has been derived as a new scaling law. Our result not only is analogous with the scaling law for weak scattering in previous works but is also applicable for a more general situation where the incident light has an arbitrary spectral degree of coherence. More discussion about cross-spectral purity of the far field is presented.

Mobile internet and technology for optical teaching reform in higher education

There are some problems in optical education such as insufficient flexibility, individuality and adaptability to students who need information and education at present. The development of mobile internet and technology provides support to solve these problems. Basic characteristics, advantages and developments of these techniques used in education are presented in this paper. Mobile internet is introduced to reform the classroom teaching of optical courses. Mobile network tool selection, teaching resources construction and reform in teaching methods are discussed. Academic record and sampling surveys are used to assess intention to adopt mobile internet and learning effect of academic major of students, the results show that high quality optical education can be offered by adopting mobile internet and technologies in traditional instruction.