Stochastic electromagnetic vortex beam and its propagation

The recent theory formulated in terms of the 2×2 cross-spectral density matrix and the propagation law of cross-spectral density are employed to investigate the stochastic electromagnetic vortex beam and its propagation characterization. Based on these, we derived the general formulae for the intensity distribution, degree of coherence and degree of polarization for stochastic electromagnetic vortex beam while propagating in free space. It is shown that the intensity distribution and the degree of polarization of the stochastic electromagnetic vortex beam propagating in free space depend on the correlation length and the topological charge of the vortex beam.     

Wide band polarizer with suspended silicon grating

In this paper, we propose an ultra broadband polarizer operating in the telecommunication wavelength band; this device consisting a single silicon suspended resonant grating layer is designed with using the inverse mathematical method and rigorous vector diffraction theory. It is shown from our calculations that the device presents extremely high reflection (R > 98%) for TE polarization light and high transmission (T > 98%) for TM polarization over ∼330 nm wavelength range; moreover, the extinction ratio is ∼100 in the central wavelength 1550 nm. Furthermore, it is found with Rigorous Coupled Wave Analysis (RCWA) and near field distribution that the extremely wide band property for TE polarization is due to the excitation of strong modulation guided modes in the design wavelength range.     

Double groove silicon grating polarizer in telecommunication wavelength band

In this paper, we propose an ultra broad band polarizer operating in the telecommunication wavelength band, this device consisting a double groove silicon grating is designed with using the inverse mathematical method and rigorous vector diffraction theory. It is shown from our calculations that the device presents extremely high reflection (R > 95%) for TE polarization light and high transmission (T > 95%) for TM polarization over ∼400 nm wavelength range, moreover, the extinction ratio is ∼30 in the central wavelength 1550 nm. Furthermore, it is found with rigorous coupled wave analysis (RCWA) that the extremely wide band property for TE polarization is due to the excitation of strong modulation guided modes in the design wavelength range.     

Polarization fluctuations of single photon states in a slant channel with non-Kolmogorov turbulence

Polarization properties of single photon states propagating through the non-Kolmogorov turbulence in a slant channel are studied based on the degree of polarization of quantum field. The degree of polarization of single photon states for linearly polarized quantum beam propagation in a slant turbulent channel are developed. Our results show that the effects of the outer scale fluctuations of atmospheric turbulence and the wavelength difference of the beams on the polarization can be ignored and the smaller inner scale of turbulence and larger zenith angle of communication channel will lead to larger fluctuations of the polarization of single-photon states. The effects of the inner scale of turbulence on polarization of single photon states are more significant for bigger refractive-index power and bigger zenith angles.     

Rigorous electromagnetic analysis of dual-closed-surface microlens arrays

In this paper, we investigated the focal performance of the dual-closed-surface microlens arrays (DCSMAs) based on rigorous electromagnetic theory and boundary element method (BEM) in the case of TE polarization. The DCSMAs are designed with different substrate thickness and different distance between microlenses. DCSMAs designed according to different wavelengths are surveyed. The DCSMAs with different incident angles are also studied. Several focusing performance measures, such as the focal spot size, the focal position on the preset focal plane, the diffraction efficiency and the normalized transmitted power, are presented. Numerical results indicate the DCSMAs with different parameters can implement focusing beams and the focal performance of DCSMAs is easily influenced by the substrate thickness and the incident wavelength. Furthermore, the optimal thickness for the maximal diffraction efficiency of the DCSMAs is given. It is expected that the DCSMAs may be used as a parallel processing device in micro-optics systems.     

Polarization properties of two Gaussian Schell-model beams in the turbulent atmosphere

General expressions are derived for the spectral degree of polarization of a beam generated by the superposition of two Gaussian Schell-model (GSM) beams propagating in a turbulent atmosphere by adopting the beam coherence-polarization matrix and Young's interference theory. We analyzed the distance of two beams, atmospheric turbulence intensity, and the location of the imaging plane affect the degree of polarization by numerical calculation. In particular, when the correlation coefficients of x and y components of the electric field are the same (i.e. δ_xx = δ_yy), the degree of polarization will obtain the same value.     

Reply to “Comment on ‘The Imbert-Fedorov shift of paraxial light beams’”

This is a reply to the Comment by Bliokh on our paper that appeared in Opt. Commun. 281 (2008) 3427. After a brief introduction of the representation theory of vector electromagnetic beams advanced in a recent paper, I point out that the Imbert-Fedorov effect is the evidence of the change of the beam parameter Θ and the polarization ellipticity σ caused by the reflection or transmission process in the linear approximation. Then I explain that it is because the linear approximation of the incident beam that we used in our paper had been assumed in previous works that we reproduced their results.     

Polarization Changes of Partially Coherent Electromagnetic Vortex Beams Propagating in Turbulent Atmosphere

We investigate the polarization change of partially coherent electromagnetic vortex beams propagating in turbulent atmosphere. It is shown that the polarization of the beams will experience changes, and the changes of the polarization are dependent on the spatial coherence, topological charges of the beams, and the degree of polarization of the source plane and the atmospheric turbulence. The results obtained may have applications in space optical communication.     

Electromagnetic Wave Transmission from Slightly Gaussian Rough Surface of Layered Medium

The electromagnetic wave transmission from the slightly rough surface of three-layered medium is studied, and formulae of the transmission coefficients for different polarizations are derived using the small perturbation method. A Gaussian rough surface is presented for describing rough surface of the layered medium, the influence of permittivity of the layered medium, the mean layer thickness of the intermediate medium, the roughness surface parameters and the incident frequency on the transmission coefficient of HH polarization are obtained and discussed with numerical implementation.     

The impact of light polarization on imaging visibility of Nth-order intensity correlation with thermal light

The relationship between the imaging visibility of arbitrary Nth-order intensity correlation with thermal light and light’s degree of polarization is investigated. It is shown that for the same order correlation, the value of visibility with partially polarized light is greater than that with natural light but smaller than that with completely polarized light, and the visibility in all three cases is remarkably enhanced as N increases.     

Broad band beam splitter based on the double-groove fused silica grating

In this paper, we propose a broad band 1 × 3 beam splitter operating in the telecommunication wavelength band under normal incidence, this device consisting of a double-groove fused silica grating layer is designed with using the inverse mathematical method and rigorous vector diffraction theory. It is shown from our calculations that the device presents excellent beam splitter ability for TE polarization light with the average diffraction efficiencies is more than 95% over ∼100 nm wavelength range, moreover, the uniformity of our beam splitter is better than 2% in the whole wavelength band. Furthermore, the physical understanding of the diffraction behaviors taking place inside the beam splitter gratings can be explained by the modal method.     

Propagation of a stochastic electromagnetic Gaussian Schell-model beam through an optical system in turbulent atmosphere

A generalized diffraction integral formula for stochastic electromagnetic beams propagating through an optical system in turbulent atmosphere is derived with the help of tensor method. Some analyses are illustrated by a numerical example relating to changes in the average intensity and the degree of polarization of an electromagnetic Gaussian Schell-model beam propagating through a double-lenses system. It is shown that the optical system has strong influence on the propagation properties of the beam. The method used in this paper can be widely applied to the propagation of astigmatic beams through an optical system in turbulent atmosphere.     

Numerical aperture invariant focus shaping using spirally polarized beams

The concept of spiral polarization is proposed as an extension of the generalized cylindrical vector beam. The focusing properties of this spatially variant polarization under high NA are studied. It can be shown that with one such polarization, the focus maintains a flat-top intensity shape independent of NA from NA = 0.82 up to NA = 0.95.     

Effect of cross-polarization of electromagnetic source on the degree of polarization of generated beam

In this paper we study the degree of cross-polarization of a beam-like field whose cross-spectral density matrix is symmetric with respect to the permutation of its spatial arguments. Formulas were derived expressing the degree of cross-polarization in terms of the generalized Stokes parameters. With the help of an uniformly polarized quasi-homogeneous model source, the effect of degree of cross-polarization of a source on the degree of polarization of the radiated beam was demonstrated, that, two sources with same spectral degrees of coherence and polarization but with different degrees of cross-polarization can generate beams that have different spectral degrees of polarization in the far field.     

Propagation of random electromagnetic beams through axially nonsymmetrical optical systems

When random electromagnetic beams passing through axially nonsymmetrical ABCD optical systems, the analytical formula for the transformation of the elements of 2 × 2 cross-spectral density matrix is obtained with the help of vector integration. We derive analytical expressions of the spectral degree of polarization, the spectral degree of coherence, and the spectral density in any output plane z > 0. Some numerical calculations are illustrated relating to the electromagnetic Gaussian Schell-model beams propagating through such optical systems.     

Binary polarization pupil filter: Theoretical analysis and experimental realization with a liquid crystal display

The Jones matrix formalism has been applied to evaluate the response of an optical system when a non-uniform polarizing pupil is introduced. With this formalism we analyze and experimentally demonstrate the properties of a binary polarization pupil filter having two regions with two orthogonal linear polarization orientations. We first study the case when no analyzer is placed behind the pupil filter, and both, the transversal and the axial behavior are described in terms of the intensity and the local state of polarization. Then it is shown how the response of the optical system can be easily changed through the orientation of an analyzer placed behind the pupil. We experimentally verified the theory using a twisted nematic liquid crystal display, which produces two orthogonal linear polarization states for two different addressed voltages.     

Tensor theory of electromagnetic radiometry

A theory of electromagnetic radiometry is built on the premise that the electromagnetic generalised radiance has a tensor structure, represented by the electric, magnetic and mixed generalised radiance tensors as fundamental quantities. They allow overcoming the limitations due to the scalar generalised radiances, proposed for characterizing stationary random electromagnetic sources. Furthermore, they provide a unified framework for completely describing the energy flux and the states of spatial coherence and polarization of random electromagnetic fields. So, the fundamental quantities of both the scalar generalised radiometry and the classical radiometry or photometry are deduced as particular cases of the tensor theory. A new procedure of analysis of (second-order) correlations, subject to the accomplishment of conservation laws, is also introduced. It reveals that (1) the primary sources of the measurable radiometric quantities associated to the random electromagnetic fields in any states of spatial coherence and polarization are the individual radiators of the radiant source (the correlations of the electric and magnetic field vectors only modulate the contributions given by those radiators) and (2) there are two physical mechanisms for the transport of measurable radiometric quantities by the electromagnetic field, i.e. the propagation of the contributions from individual radiators and their redistribution over each wavefront on propagation. The term redistribution refers to the transfer of portions of the measurable quantity over the wavefronts on propagation, without change its total value over each wavefront. In this context, a physical meaning is given to the negative values of the generalised radiance, which gives new insight about the Poynting’s theory of energy transport.     

Wavelength dependence of the phase retardation of a quarter-wave plate

We describe an optical heterodyne polarization interferometer that can be efficiently used for the precision measurement of the change in the state of polarization of a light wave induced by polarizing optical devices. This technique is used to measure the change with wavelength of the phase retardation of a quarter-wave plate. A theoretical derivation is presented to permit computation of the wavelength dependence of the phase shift induced by a quarter-wave plate.     

Coherent and incoherent polarization encoding of electromagnetic fields

We study a method generating certain distributions of the degree and state of polarization of a light field across a transverse beam cross-section. We use the introduced polarization encoding scheme to study the distribution of polarization ellipses in a cross-section of a beam generated by superposing two encoded beams, the effects of coherence relation between the input beams on this distribution were theoretically analyzed and illustrated by contour plots of the parameters representing polarization ellipses.     

斜程大气湍流中激光回波的闪烁指数

根据光波斜程传输理论以及随高度变化的ITU-R大气折射率结构常数模型,考虑内尺度及从发射机到目标和从目标到接收机双斜程路径影响的条件下,应用修正Hill湍流折射率起伏功率谱,对反射器目标激光回波闪烁指数进行了研究。推导了回波闪烁指数随菲涅耳率的变化关系,数值分析了不同内尺度、传输距离、激光波长以及目标高度对回波闪烁指数的影响。结果表明:内尺度和目标高度对回波闪烁指数的影响要远大于波长和传输距离的影响。