The polarization effect of a laser in multiphoton Compton scattering

The multiphoton Compton scattering in a high-intensity laser beam is studied by using the laser-dressed quantum electrodynamics(QED) method, which is a non-perturbative theory for the interaction between a plane electromagnetic field and a charged particle. In order to analyze in the real experimental condition, a Lorentz transformation for the cross section of this process is derived between the laboratory frame and the initial rest frame of electrons. The energy of the scattered photon is analyzed, as well as the cross sections for different laser intensities and polarizations and different electron velocities. The angular distribution of the emitted photon is investigated in a special velocity of the electron, in which for a fixed number of absorbed photons, the electron energy will not change after the scattering in the lab frame.We obtain the conclusion that higher laser intensities suppress few-laser-photon absorption and enhance more-laser-photon absorption. A comparison between different polarizations is also made, and we find that the linearly polarized laser is more suitable to generate nonlinear Compton scattering.     

Numerical study on the wavelength-dependent polarization of light scattered by aqueous droplets for RGB spectrums

Based on Lorenz-Mie scattering theory, the transformation matrix of an aqueous droplet is derived analytically. By employing single scattering approximation and log-normal size distribution function, the DOP (degree of polarization) of the light scattered by a unit volume of aqueous droplets for RGB (red, green and blue) spectrums is studied. In our study, the wavelength-dependent complex refractive index for water with fine resolution is novelly obtained by using Piecewise Interpolation method based on Segelstein's refractive index data. The analytical results reveal that extrema of the DOP which is dependent on the relative intensities of the orthogonal polarizations are associated with scattering angles, and, for RGB spectrums, increasing wavelength can alleviate the influence of the resonance on the orthogonal polarizations and the DOP.     

Renormalized dispersion of elementary excitations in spinor polariton condensates

We analyse the polarization of spinor polariton condensates and corresponding dispersions of elementary excitations. We have considered the effects of magnetic field induced splitting in circular polarizations and residual splitting in linear polarizations in the ground state provided by the cavity asymmetry. We show that anisotropic polariton–polariton interactions fully compensate the Zeeman splitting in circular polarizations below the critical magnetic field, thus leading to the spin-Meissner effect for the polariton condensates. We also analyzed the effect of polariton–polariton interactions on the stability of the gap in linear polarizations characteristic for anisotropic microcavities. It was shown that in realistic systems this gap increases with concentration of the particles, thus contributing to the stability of the pinning of linear polarization of photoemission in semiconductor microcavities for pump intensities above the stimulation threshold.     

Photonic band gap architectures for holographic lithography

Using symmetry considerations, we identify three families of large photonic band-gap (PBG) architectures defined by the isointensity surfaces of four beam laser interference. For particular choices of beam intensities, directions, and polarizations, we obtain a diamondlike crystal, a novel body-centered cubic architecture, and a simple cubic structure with PBG to center frequency ratios of 25%, 21%, and 11%, respectively, when the isointensity surface defines a silicon (dielectric constant of 11.9) to air boundary.     

Doubly resonant photon echoes in a three-level system

This paper deals with the photon echoes associated with two optical pulses of different frequencies, resonant to a three-level system, and reveals the existence of anomalous echoes, appearing at times corresponding to the correlations between the inhomogeneous broadenings for different spectral lines. The intensities, direction of propagation and polarizations of the echoes are analyzed quantitatively.     

Structure and dynamics of the Lu<Subscript>2</Subscript>Si<Subscript>2</Subscript>O<Subscript>7</Subscript> lattice: Ab initio calculation

The ab initio calculations have been carried out for the crystal structure and Raman spectrum of a single crystal of lutetium pyrosilicate Lu₂Si₂O₇. The types of fundamental vibrations and their frequencies and intensities in the Raman spectrum for two polarizations of the crystal have been determined. The calculations have been performed within the framework of the density functional theory (DFT) using the hybrid functionals. The ions involved in the vibrations have been identified using the method of isotopic substitution. The results of the calculations are in good agreement with the experiment.     

Study on optical wave scattering from slightly Gaussian rough surface of layered medium

The optical wave scattering from the slightly rough surface of three-layer medium is studied. The formulaes of the scattering coefficients for different polarizations are derived using the small perturbation method.     

Second-order Raman spectra of CsCl single crystals

The second-order Raman spectra of CsCl single crystals have been measured at room temperature for different Raman polarizations and crystal orientations. With the help of the calculated selection rules for a CsCl-type lattice, observed nineteen peaks and shoulders were assigned by the critical point analysis based on the neutron scattering data. By comparing the observed Raman intensities with the thermally weighted two-phonon density-of-states calculated by using a simple shell model, it has turned out that though the measured spectra are dominantly determined by the two-phonon density-of-states, the effect of the q-dependence of the polarizability cannot entirely be neglected.     

Intensity-controlled interactions between vectorial spatial solitary waves in quadratic nonlinear media

We numerically investigate the interaction of vectorial solitary waves propagating in a bulk crystal with a phase-matchable quadratic nonlinearity. We obtain coalescence, steering, crossing, or repulsion by controlling the launched intensities in two orthogonal polarizations without any coherent seed at the second harmonic.     

微型化频率选择表面的设计研究

利用容性表面与感性表面之间的耦合机理能够制备微型化频率选择表面(MEFSS),周期单元尺寸将不受工作波长限制.为了提高MEFSS角度与极化的稳定性,展宽MEFSS的-3 dB带宽,文章结合传统频率选择表面"Y"形单元,利用"Y"图形构造容性表面的贴片单元与感性表面的网栅单元且以正三角形栅格拓展周期单元,采用矢量模匹配法对MEFSS栅格排布及其他结构参数变化进行精确计算.通过镀膜与光刻技术在0.15 mm厚聚酰亚胺膜两侧制备容性表面、感性表面并利用自由空间法测试.计算与实验结果均表明,采用正三角形栅格排布的MEFSS,-3 dB带宽达到7.6 GHz,不同极化下60°扫描时中心频点稳定在f₀,为MEFSS应用于曲面天线罩时提供理论与实验参考依据. 关键词： 天线罩 微型化频率选择表面 容性表面 感性表面     

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.     

Transmission of encoded information based on antiphase dynamics

We propose a method for secure information encoding and transmission that exploits (i) the sensitivity of antiphase dynamics to the relative phase of time-dependent intensities in multimode free-running Fabry-Perot lasers and (ii) the nonreciprocal independence of antiphased states oscillating in orthogonal polarizations. The logical states are chaotic attractors. The signal sent by the transmitter is only part of the key. The total key is the signal plus the receiver. The signal generates the message only in the correct receiver.     

Self-rotation of elliptically polarized light in Doppler-broadened rubidium atoms

We present a theoretical and experimental study of self-rotation of incident elliptically polarized light on a rubidium atomic vapor. We construct density matrix equations, which are then solved numerically, and further averaged over atomic transit times and a Maxwell-Boltzmann velocity distribution. We calculate the rotation angle as a function of detuning for various laser intensities and polarizations. We compare the calculated results with experimental results and find good agreement between them.     

负折射率材料用于表面波传感的特性分析

利用严格电磁理论分析了负折射材料界面上激励表面波的相关特性,证明两种偏振入射都能在负折射材料与正折射材料界面上激发表面波,并推导出了相应表面波的传播波矢和激发条件.针对负折射材料在表面波传感方面的应用,对膜厚选择,偏振态,测量范围,线性度等性能参量进行了具体分析,与传统的金属表面等离子波传感器相比,使用负折射材料在灵敏度相当的情况下,能有效提高线性度,增大测量范围,提高信噪比.     

Linear dichroism and magnetic circular dichroism of acenaphth[1,2-a]acenaphthylene

Ultraviolet-visible polarized absorption spectra of acenaphth[1,2-a]acenaphthylene have been determined from low-temperature measurements of linear dichroism in stretched polyethylene. The magnetic circular dichroic spectrum has been measured in solution. Transition energies, polarizations, and relative intensities, as well as the absolute signs of B terms of low-energy transitions are in good agreement with results of π-electron calculations and with simple qualitative arguments, which also account for the close similarity to the known spectra of acenaphthylene.     

Polarized single-crystal specular reflectance spectra of (TMTSF)2ClO4 in the visible and ultraviolet

Single-crystal specular reflectance spectra of three polarizations of (TMTSF)₂ClO₄ in the visible and ultraviolet regions and their Kramers-Kronig-transformed absorption spectra are reported. Earlier reports of visible transitions are confirmed with the addition of integrated intensities, and several new transitions are reported quantitatively in the ultraviolet.     

Control of light polarization by acousto-optic diffraction from leaky acoustic wave in LiNbO₃

The acousto-optic control of light polarization due to diffraction by leaky acoustic waves in ZX-LiNbO? has been demonstrated. The randomly polarized light of 633 nm wavelength is converted by the anisotropic diffraction into two beams with mutually orthogonal polarizations, the relative intensities of which depend on the light incidence angle and acoustic frequency. Variation in acoustic frequency from 108 to 112 MHz rotates the polarization of the output optical beam by 90°. The acousto-optic control is accomplished entirely by electronic means and can be applied for implementation of fast polarization converters.     

Radar backscattering from Gerstner's sea surface wave

In the framework of a two-scale scattering model, radar backscattering from the rough sea surface was considered. The sea surface was modelled as a superposition of a nonlinear, large-scale Gerstner's wave and small-scale resonant Bragg scattering ripples. The zero-order diffracted field was found by a geometrical optics approach, with shadowing taken into account, and by an 'exact' solution of the diffraction problem obtained numerically. For vertical and horizontal polarizations, the spatial distribution of specific scattering cross sections along the large-scale wave was obtained. The spatially averaged specific backscattering cross sections, as well as the mean Doppler frequency shifts at both polarizations, obtained by the geometrical optics approach are compared with those obtained by using the 'exact' solution of the large-scale diffraction problem. The roles of shadowing and multiple wave scattering processes are discussed, and qualitative explanations of the difference between these two approaches are given.     

Effective quantum spin systems with trapped ions

We show that the physical system consisting of trapped ions interacting with lasers may undergo a rich variety of quantum phase transitions. By changing the laser intensities and polarizations the dynamics of the internal states of the ions can be controlled, in such a way that an Ising or Heisenberg-like interaction is induced between effective spins. Our scheme allows us to build an analogue quantum simulator of spin systems with trapped ions, and observe and analyze quantum phase transitions with unprecedented opportunities for the measurement and manipulation of spins.