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A so-called cylindrical localized approximation, allowing one to speed up the evaluation of beam shape distributions in generalized Lorenz-Mie theory for circular infinitely long cylinders, has been previously introduced and, in the case of Gaussian beams, rigorously justified. In this paper, we examine and demonstrate the validity of this approximation for arbitrary shaped beams. [ABSTRACT FROM AUTHOR]

Reshaping of a Gaussian laser beam into a uniform or other intensity distribution is required for various applications. The laser beam shaping system with a radial birefringent filter is presented in this paper. With such a system the Gaussian beams can be transformed into uniform or annular beams. The theory and simulation of the proposed systems are described in detail. The primary advantage of such a system is that the out beam profile can be tunable with the rotation of the radial birefringent element. [ABSTRACT FROM AUTHOR]

This paper presents a numerical method for calculating the scattered field when a vertically polarized Gaussian beam is incident on a flat or slightly rough conducting surface at a grazing angle and the refractive index of the propagation medium has a profile which is not constant. The method is a solution to the parabolic approximation of the full wave equation. The results presented are taken for a linear and log-linear refractive index profile. [ABSTRACT FROM AUTHOR]

We have used the framework of the dispersion equation to study coherent Smith–Purcell (SP) radiation induced by a relativistic magnetized electron beam in the absence of a resonator. As an important example of the application of the obtained results of our previous paper JMO v.57, 2060, (2010) the growth rate of SP FEL in the case with a rectangular grating was calculated. The growth rate of the instability is proportional to the square root of the electron beam current. The calculated results are consistent with the experimental data obtained by Urata et al. [Phys. Rev. Lett. 80, 516 (1998)]. [ABSTRACT FROM PUBLISHER]

In this paper we discuss the reconstruction process of one-photon mixed states of partially polarised light. To solve this issue, we obtain the Stokes parameters by means of the degree of polarisation. The density operator describing the examined state is represented with these parameters. In the proposed two-beams method the degree of polarisation is measured on the analysed beam combined with reference beams containing photons with a settled state of polarisation. Coupling these beams allows one to obtain the Stokes parameters from the intensity contrast behind the rotating polariser. We discuss the influence of the quantum uncertainty on this technique of one-photon states reconstruction and we consider it for three aspects – the possibility of reducing the number of reference beams that are needed, the optimal state of polarisation of reference beams and the accuracy of the reconstruction method. [ABSTRACT FROM PUBLISHER]

In this paper, we propose two ways of Dicke state generation using single photons and weak coherent pulse resorting to Kerr nonlinearities. By interference of two coherent beams, the Dicke state are realized in polarization and photon number degrees of freedom. By performing homodyne detection on the coherent states, the multi-particle entangled Dicke state can be generated with a high probability. The realization of the protocols are more flexible as the phase differences can be easily distinguished during homodyne detection. [ABSTRACT FROM AUTHOR]

A new kind of laser beam called the decentred elliptical flat-topped light beam (DEFTB) is introduced in this paper by using a tensor method. Based on the generalized Collins integral, the propagation formula for a DEFTB passing through an axially nonsymmetrical paraxial optical system is derived through vector integration. The derived formula can be reduced to the formulae for the generalized decentred elliptical Gaussian beam and elliptical flat-topped light beam under certain conditions. As a typical application example of the derived formula, the propagation characteristics of a DEFTB in a thin lens system are calculated and discussed. Furthermore, the generalized laser beam arrays with rectangular symmetry and radial symmetry by using DEFTBs as fundamental modes are constructed and the propagation properties of both a coherent and an incoherent combination of DEFTBs in the thin lens system with numerical examples are investigated. [ABSTRACT FROM AUTHOR]

When developing a compact holographic storage system it is beneficial to use a reflection-type arrangement, where the entire optical system is on the same side of the storage material. For reflection type holographic discs, it is important to use half-cone-shaped spherical reference beams to avoid the ghost images caused by phase conjugate readout. The goal of this paper is to look for appropriate engineering tools to model diffraction efficiency of finite volume holograms created by half-cone-shaped reference beams. Two numerical methods – volume integral and beam propagation – were applied to calculate the shift selectivity curves. Simulation results show significant discrepancies between the shift selectivity curves corresponding to the approximated analytical equation and the numerically calculated shift selectivity curves; there are no Bragg zeros and there are no selective and nonselective directions. Beside the shift selectivity curves, track, focus, tilt and wavelength tolerance values are shown for finite volume holograms. [ABSTRACT FROM AUTHOR]

The most direct and simple method to calculate analytically the propagation in the far field of a coherent beam with a rectangular symmetry and a super-Gaussian-like irradiance profile involves the use of the convolution theorem. In this paper we extend this method to a circularly symmetric beam, and hence from the Fourier transform to the zero-order Hankel transform. Then, we examine the more complex case of super-Gaussian-like beam irradiance shapes with an axial shadow, as those emitted by unstable resonators with diffraction output coupling or with a variable-reflectivity mirror. The analytical results obtained by approximating the super-Gaussian-like beam with a convolution function and applying the Hankel transform are in excellent agreement with those obtained by numerical simulations. [ABSTRACT FROM AUTHOR]

With the help of the extended Huygens-Fresnel principle and the spherical-wave short-term mutual coherence function, an analytical expression was derived for the short-term average intensity of a cosh-Gaussian beam through Kolmogorov turbulence. As special cases, the properties of the short-term average intensity with different propagation distances and parameters are studied. In addition, a comparison is presented of average intensity between short exposure and long exposure. The results show that the effect of turbulence on long- and short-term average intensity is different for different factors of the cosh part. [ABSTRACT FROM AUTHOR]

The closed-form expressions for the spectral degree of coherence and the width of the spectral degree of coherence of Gaussian-Schell model (GSM) beams propagating through atmospheric turbulence are derived. The influence of atmospheric turbulence on the spectral correlation properties of GSM beams is studied both analytically and numerically. A comparison between the width of the spectral degree of coherence and that of the spectral intensity of GSM beams propagating through atmospheric turbulence is also given. Some interesting results are obtained, which are different from those obtained previously, and are explained physically. [ABSTRACT FROM AUTHOR]

The far-field anomalous spectral behaviours of a space-time-dependent Gaussian pulsed beam passing through a rectangular aperture are studied. By expanding a hard aperture function into a finite sum of complex Gaussian functions and starting from the Fresnel diffraction integral, the approximate analytical expression for the spectral intensity of a space-time-dependent Gaussian pulsed beam passing through a rectangular aperture is derived. Meanwhile, the corresponding closed-forms for the slit and the unapertured cases are also given as special cases of the general results. The red and blue shifts and the spectral intensity distribution are studied and illustrated with numerical calculations. Specifically, it is shown that the spectral switch takes place when the truncation parameter is equal to particular values or the observation position is at the critical diffraction angle. The possibility of tunable spectral switching in the far field with an apertured pulsed beam by varying the size of the rectangular aperture is highlighted. [ABSTRACT FROM AUTHOR]

Based on the extended Huygens–Fresnel principle, the spreading of partially coherent flattened Gaussian beams propagating through turbulent media is studied by using the incoherent superposition of higher-order Hermite–Gaussian beams. The mean-squared width of partially coherent flattened Gaussian beams in turbulence is derived. It is shown that the spreading of partially coherent flattened Gaussian beams increases with increasing turbulent parameter and beam order N . However, the difference between the relative spreading of partially coherent flattened Gaussian beams in turbulent media and in free space reduces as N increases. Therefore, partially coherent flattened Gaussian beams with high N are less sensitive to the effects of turbulence than those with lower N . [ABSTRACT FROM AUTHOR]

A symmetrical iterative Fourier-transform algorithm (IFTA) using a combination of phase and amplitude freedom for the design of diffractive optical elements for highly precise laser beam shaping is presented. We compare this method with the basic IFTA and the symmetrical IFTA exclusively using phase freedom, and the basic IFTA using both phase and amplitude freedom, by employing these methods for super-Gaussian beam shaping. While the latter three methods fail to produce satisfactory solutions, the first method results in a beam non-uniformity error of 0.44% and a theoretical efficiency of 97.2%. Moreover, the new approach avoids the use of the trial-and-error method for finding the appropriate modified Fourier-domain constraints during the iteration, which can be difficult for some beam-shaping problems. [ABSTRACT FROM AUTHOR]

The concept of partially coherent J 0 -correlated Schell-Model (JSM) beams is extended to the nonparaxial regime. By using the generalized Rayleigh-Sommerfeld diffraction integral, analytical propagation equations of nonparaxial JSM beams in free space are derived. Under the paraxial approximation our results reduce to the corresponding paraxial ones. The free-space propagation properties of nonparaxial JSM beams are illustrated with numerical examples. A comparison with paraxial JSM beams shows that the nonparaxial approach should be used if the parameters f and s are not small. [ABSTRACT FROM AUTHOR]

By introducing a hard aperture function into a finite sum of complex Gaussian functions, an approximate analytical expression for a Gaussian beam passing through a paraxial ABCD optical system with an annular aperture has been derived. The results could be reduced to the case of circular black screen or circular aperture. Some numerical simulations are also performed and illustrated for the propagation characteristics of a Gaussian beam through a paraxial ABCD optical system with an annular aperture, a circular black screen or a circular aperture. [ABSTRACT FROM AUTHOR]

The propagation characteristics of the kurtosis parameters of a standard Hermite—Gaussian (SHG) beam and of an elegant Hermite—Gaussian (EHG) beam, each passing through a fractional Fourier transformation (FRFT) system with a spherically aberrated lens, are studied in detail. Some numerical calculations are made by introducing an efficient algorithm, based on the Collins diffraction integral formula. The resulting graphs illustrate the striking difference between ideal FRFT systems and those with a spherically aberrated lens. The kurtosis parameters of both SHG and EHG beams passing through a type I Lohmann system with a spherically aberrated lens are seen to change with the fractional order periodically and the fundamental period is 4, but for type II the fundamental period is 2. Different values of spherical aberration coefficients affect the kurtosis parameters in greatly different ways. The values of the kurtosis parameters of a SHG beam passing through either type of Lohmann system with a spherically aberrated lens are no longer equal to those of an EHG beam, even when they have the same fractional orders and the same spherical aberration coefficients. [ABSTRACT FROM AUTHOR]

Based on the generalized Huygens-Fresnel diffraction integral, closed-form expressions for the relative phase shift of Laguerre-Gaussian beams propagating through an apertured paraxial optical ABCD system are derived. The dependence of the relative phase shift on the beam and system parameters, and the condition for eliminating phase shift are analysed and illustrated with numerical examples. [ABSTRACT FROM AUTHOR]

We derive an analytical propagation expression of the finite energy Airy-Hermite-Gaussian beam propagating in a uniaxial crystal orthogonal to the optical axis, and calculate numerical examples to investigate the influences of the propagation distance and the ratio of the extraordinary refractive index to the ordinary refractive index on the beam profile. In addition, we also examine the intensity distribution of the beam propagating in the uniaxial crystals at different observation sections. Our research shows that the initial beam profile of the beam remains nearly invariant for a short propagation distance in the crystal. However, as propagation distance continues to increase, the beam width will gradually enlarge, where the diffusion velocities of the beam in theXandYdirections are different. Moreover, both the ratio of the extraordinary refractive index to the ordinary refractive index and the Hermite order number also strongly affect the beam profile in a uniaxial crystal. Our work may find some potential applications in optical trapping and nonlinear optics involving in the special beam profile. [ABSTRACT FROM AUTHOR]

The conversion of high-mode solitons propagating in Strongly Nonlocal Nonlinear Media (SNNM) in three coordinate systems, namely, the elliptic coordinate system, the rectangular coordinate system and the cylindrical coordinate system, based on the Snyder–Mitchell Model that describes the paraxial beam propagating in SNNM, is discussed. Through constituting the trial solution with modulating the Gaussian beam by Ince polynomials, the closed-solution of Gaussian beams in elliptic coordinate is accessed. The Ince–Gaussian (IG) beams constitute the exact and continuous transition modes between Hermite–Gaussian beams and Laguerre–Gaussian (LG) beams, which is controlled by the elliptic parameter. The conditions of conversion in the three types of solitons are given in relation to the Gouy phase invariability in stable propagation. The profiles of the IG breather at a different propagating distance are numerically obtained, and the conversions of a few IG solitons are illustrated. The difference between the IG soliton and the corresponding LG soliton is remarkable from the Poynting vector and phase plots at their profiles along the propagating axis. [ABSTRACT FROM AUTHOR]

Spectral changes of a partially coherent standard or elegant Laguerre–Gaussian (LG) beam propagating in turbulent atmosphere were studied numerically. Our results show that the spectral changes of a partially coherent standard or elegant LG beam in turbulent atmosphere are determined by both the structure constant of the turbulent atmosphere and the initial beam parameters. Furthermore, it is found that a partially coherent elegant LG beam is less affected by the turbulent atmosphere than a partially coherent standard LG beam from the aspect of the on-axis spectral shift, and this advantage is enhanced for small structure constant, small beam waist size, large mode orders, and large transverse coherence length. Our results will be useful in long-distance free-space optical communications. [ABSTRACT FROM AUTHOR]

Evolution properties of the complex degree of coherence of a partially coherent Laguerre–Gaussian beam (LGB) on propagation in free space and turbulent atmosphere are studied comparatively with the help of the general propagation formula for such beam. It is found that the behavior of the complex degree of coherence of a partially coherent LGB on propagation in turbulent atmosphere is much different from that in free space and is closely related to the initial beam parameters and the structure constant of the turbulent atmosphere. The distribution of the modulus of the complex degree of coherence of the partially coherent LGB finally becomes of Gaussian distribution at long propagation distance in turbulent atmosphere, and it becomes of Gaussian distribution more slowly with the increase of the mode orders, beam width and wavelength. Our results will be useful in long-distance free-space optical communications. [ABSTRACT FROM PUBLISHER]

In this work we propose an implementation of a new intra-cavity beam shaping technique to vary the intensity distribution of the fundamental mode in a resonator cavity while maintaining a constant intensity distribution at the output. This method can be useful for fitting a transversal intensity profile of the required mode with a pump beam profile in the region of the active medium to increase mode discrimination. [ABSTRACT FROM PUBLISHER]

Tailored compositions of transverse modes provided by mathematical generating functions are exploited for the synthesis of multimode laser beams in free space. We show that analytical equations which are available for the generating functions provide physical insight into modal phase and power balance in multimode coherent light beams. Multimode coherent beams were created by methods of diffractive optics implementing the generating functions. Experimental and computer simulated results demonstrate a good match. [ABSTRACT FROM AUTHOR]

The use of additional adaptive optics to manipulate the beacon in an adaptive optics system for the human eye opens up many opportunities. Possibilities include better beacon creation, correction of gross aberrations that the beam acquires as it passes into the eye, symbiotic beams to guide or locate a probe or medical beam, and examination of the higher order aberrations experienced by the beam as it enters the eye. We describe the use of active optics for creation of the beacon in an adaptive optics system that incorporates a fundus imaging arm. In describing the possibilities for beacon shaping and steps that may be employed to use this to create a sharper or more versatile beacon, we determine the effects of such shaping on the performance of the system. Results are presented for both model and human eyes. The beacon shaping incorporates Bessel beam creation with tip-tilt and defocus correction from a mask on a spatial light modulator. Visual feedback from images of the beacon as it appears at the retina is used to refine it. [ABSTRACT FROM AUTHOR]

Based on the Huygens-Fresnel principle and Rytov method, the on-axis scintillation index is derived for hollow Gaussian beams (HGBs) in weak turbulence. The relationship between bit error rate (BER) and scintillation index is found by only considering the effect of atmosphere turbulence based on the probability distribution of intensity fluctuation, and the expression of the BER is obtained. Furthermore, the scintillation and the BER properties of HGBs in turbulence are discussed in detail. The results show that the scintillation index and BER of HGBs depend on the propagation length, the structure constant of the refractive index fluctuations of turbulence, the wavelength, the beam order and the waist width of the fundamental Gaussian beam. The scintillation index, increasing with the propagation length in turbulence, for the HGB with higher beam order increases more slowly. The BER of the HGBs increases rapidly against the propagation length in turbulence. For propagating the same distance, the BER of the fundamental Gaussian beam is the greatest, and that of the HGB with higher order is smaller. [ABSTRACT FROM AUTHOR]

Based on the generalized Huygens-Fresnel integral, propagation of partially coherent Lorentz and Lorentz-Gauss beams through a paraxial ABCD optical system in a turbulent atmosphere was investigated. Analytical propagation formulae were derived for the cross-spectral densities of partially coherent Lorentz and Lorentz-Gauss beams. As an application example, the focusing properties of partially coherent Gaussian, Lorentz and Lorentz-Gauss beams in a turbulent atmosphere and in free space were studied numerically and comparatively. It is found that the focusing properties of such beams are closely related to the initial coherence length and the structure constant of turbulence. By choosing a suitable initial coherence length, a partially coherent Lorentz beam can be focused more tightly than a Gaussian or Lorentz-Gauss beam in free space or in a turbulent atmosphere with small structure constant at the geometrical focal plane. [ABSTRACT FROM AUTHOR]

The problem of the generation of stable (quasi-stable) 3+1D light bullets in nonlinear media is addressed. We consider a medium with a two-component relaxing cubic nonlinearity, and non-relaxing quintic one. It is shown that a special adjustment of the pulse duration and the parameters of the two-component relaxing nonlinearity enables one not only to suppress distortions of the temporal pulse envelope and self-induced frequency shift, but to suppress a destructive effect of the azimuthal instability of vortex pulsed beams as well. [ABSTRACT FROM AUTHOR]

We present a scheme based on the use of bright entangled twin beams for the calibration of analog photodiodes, providing an extension of the schemes for calibrating photon-counting detectors with photon pairs. Previous proposals for the calibration of analog photodiodes with entangled beams are based on a stimulated parametric process operating in the low-gain regime. We start by showing that in those proposals it is necessary to know the exact value of the gain as any error in estimating it will lead to an error in the calibration of the quantum efficiency. We then introduce a technique that is independent of the gain, thus eliminating the uncertainty introduced from errors in estimating the gain or experimental fluctuations of parameters that affect the gain. A proof of principle implementation of this technique using bright twin beams obtained from a four-wave mixing process in rubidium vapor shows its viability for the calibration of analog photodiodes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We present the theoretical and the numerical investigations of the control effect of a left-handed material (LHM) slab with third-order nonlinearity on the nonlinear propagation and the self-focusing of high-power Gaussian beams in a conventional self-focusing Kerr medium. Analytical solutions for the beam spatial properties and the self-focusing distance are derived. It is found that, in the conventional self-focusing Kerr medium, the beam diverging and the beam converging can be enhanced and suppressed, respectively, by the nonlinear LHM slab, and both the enhancing and the suppressing can be reversed by adjusting the distance between these two media. The self-focusing is also found to be enhanced or suppressed freely, and the variation of self-focusing distance takes on an interesting waving pattern. Moreover, computer simulations demonstrate the anomalous variation of self-focusing distance with the focusing property of the incident beam. [ABSTRACT FROM AUTHOR]

Based on the Collins diffraction integral formula and the fact that a hard-edged-aperture function can be expanded into a finite sum of complex Gaussian functions, the propagation of a four-petal Gaussian beam passing through an apertured fractional Fourier transform (FRFT) optical system has been studied in detail. Some typical numerical examples are given to illustrate the properties of the four-petal Gaussian beam in the FRFT plane. The results indicate that the intensity distributions of the beam in the FRFT plane are closely related to not only the fractional order but also the beam parameters and the aperture parameters. [ABSTRACT FROM AUTHOR]

The scintillation properties of a rectangular dark hollow beam (DHB) in a weak turbulent atmosphere are investigated. Explicit expression for the on-axis scintillation index of a rectangular DHB is derived. It is found that the scintillation index value of a rectangular DHB can be smaller than that of Gaussian, elliptical Gaussian and rectangular flat-topped beams in a weak turbulent atmosphere under certain conditions. Our results will be useful in long-distance free-space optical communications. The scintillation properties of a rectangular DHB are closely controlled by its initial beam parameters. [ABSTRACT FROM AUTHOR]

The far-field directionality of partially coherent flat-topped beams propagating through atmospheric turbulence is studied. The closed-form expressions for the mean squared beam width and angular spread of partially coherent flat-topped beams propagating through atmospheric turbulence are derived. It is shown that two partially coherent flat-topped beams may generate the same angular spread, and there exist equivalent partially coherent flat-topped beams which may have the same far-field directionality as a fully coherent Gaussian beam in free space and also in atmospheric turbulence. The far-field directionality of Gaussian Schell-model (GSM) beams in atmospheric turbulence is treated as a special case of partially coherent flat-topped beams. The theoretical results are illustrated by numerical examples and interpreted physically. [ABSTRACT FROM AUTHOR]

Considering an isotropic medium-uniaxial crystal interface, the coincidence of the two refracted rays is analysed. Possible solutions are shown by means of an algebraic, not just a numerical formulation. From the obtained solutions, for certain directions of the optical axis of the crystal, there are three directions in the crystal for which both rays coincide. Detailed analysis shows that there are three incidence angles for certain values of the index of the isotropic medium. [ABSTRACT FROM AUTHOR]

Starting from the Huygens-Fresnel diffraction integral, the recurrence expressions for the power spectra of pulsed Hermite-Gaussian (H-G) beams focused by a dispersive aperture lens are derived and the spectral anomalies of pulsed H-G beams in the focused field are studied. Numerical results are given to illustrate the dependence of spectral anomalies' behavior on the pulse parameters, truncation parameter and material dispersion of the lens. The potential applications of spectral anomalies of ultrashort pulsed beams in information encoding and information transmission are considered. [ABSTRACT FROM AUTHOR]

The description of a Lorentz beam is directly obtained from Maxwell's equations. Based on the vector angular spectrum representation of Maxwell's equations and the method of stationary phase, the analytical TE and TM terms of the Lorentz beam have been presented in the far field. The TE term is located at the y axis, and the TM term the x axis. The light intensity distributions of the Lorentz beam and its TE and the TM terms are depicted in the far field reference plane. The influences of the inequality of the transverse beam waists on the light intensity distributions of the Lorentz beam, its TE and TM terms are also analyzed. Moreover, the vectorial structure of the Lorentz beam is compared with that of the Gaussian beam. Due to the relatively small diffraction effect, the beam spot of the Lorentz beam is smaller than that of the Gaussian beam. This research reveals the vectorial composition of the Lorentz beam. [ABSTRACT FROM AUTHOR]

The analytical propagation equation of M×N Hermite-Gaussian (H-G) beams, which are combined incoherently and propagate through atmospheric turbulence, is derived, which enables us to study their propagation properties and far-field beam quality. The propagation of M×N Gaussian beams through atmospheric turbulence and M×N H-G beams in free space are treated as special cases of our general result. The power in the bucket (PIB), β-parameter and Strehl ratio are chosen as the parameters characterizing the beam quality in the far field. The dependence of PIB, β-parameter and Strehl ratio of M×N H-G beams through atmospheric turbulence on the refraction index structure constant Cn², beam numbers M, N, mode indices m, n and separate distances xd, yd is illustrated numerically and interpreted physically. It is found that M×N H-G beams are less sensitive to the effects of turbulence than M×N Gaussian beams. [ABSTRACT FROM AUTHOR]

Based on the vectorial structure of non-paraxial electromagnetic beam and the non-paraxial vectorial moment theory of light beam propagation, the beam waists, the divergence angles and the beam propagation factors of TE and TM terms have been presented for non-paraxial TE vector Gaussian beam. The formulae obtained are further discussed at the highly non-paraxial and paraxial cases. Their respective maximum divergence angles are given at the highly non-paraxial case. When reducing to the paraxial case, the beam propagation factors of TE and TM terms are smaller than unity, which results from their special energy flux distribution. As TE and TM terms can be detached in the far field, they can be applied in the optical storage and collimation domains. [ABSTRACT FROM AUTHOR]

We investigate non-Gaussian states of light as ancillary inputs for generating nonlinear transformations required for quantum computing with continuous variables. We consider a recent proposal for preparing a cubic phase state, find the exact form of the prepared state and perform a detailed comparison to the ideal cubic phase state. We thereby identify the main challenges to preparing an ideal cubic phase state and describe the gates implemented with the non-ideal prepared state. We also find the general form of operations that can be implemented with ancilla Fock states, together with Gaussian input states, linear optics, squeezing transformations, and homodyne detection with feed forward, and discuss the feasibility of continuous variable quantum computing using ancilla Fock states. [ABSTRACT FROM AUTHOR]

Lateral displacement and its mechanism in asymmetric layered configuration are investigated. It is shown by the stationary-phase approach that displacements of both the transmitted and reflected beams can be positive as well as negative, and their magnitude can be greatly enhanced at transmission resonances. Numerical simulations show that for a well-collimated incident beam, if the norms of transmission and reflection coefficients are approximately constant within the peak of the angular-spectrum distribution of the beam, the transmitted and reflected beams can undergo lateral displacement without distortion, as long as the thickness of the layer satisfies a restriction. It is concluded that lateral displacement is not caused by beam distortion, but the result of reshaping the multiply transmitted (or reflected) beams. [ABSTRACT FROM AUTHOR]

Misaligned cavities can be described by a 3 × 3 extension of the well-known ABCD matrix approach to aligned cavities. There is a corresponding Huygens integral (HI) formulation for the evolution of the field within such a cavity. We derive a differential ‘master’ equation (ME) formulation which yields identical eigenmodes and eigenvalues to this HI. This ME is fully equivalent to the HI for linear problems, while providing a more convenient route to the analysis of nonlinear behaviour in such cavities. [ABSTRACT FROM AUTHOR]

The diffraction properties of volume holographic gratings are studied when the gratings are illuminated by an ultrashort pulsed beam with different polarization states. The developed coupled wave theory of Kogelnik is used. Considering the dispersion effect of the grating media, solutions for the diffracted and transmitted intensities, diffraction efficiencies and the bandwidths of the gratings are given in transmission volume holographic gratings and reflection volume holographic gratings. The bandwidths of the gratings are reduced by the dispersion effect of the grating media. They also have different influences on the diffraction of an ultrashort pulsed beam with different polarization states. For different values of the ratio of the spectral bandwidth of the input pulse to that of the grating, the changes of the spectral and temporal distributions of the diffracted intensities, as well as the diffraction efficiencies of the gratings are shown. [ABSTRACT FROM AUTHOR]

Forces exerted upon a dielectric cylinder of infinite length and arbitrary, or circular, cross-section by the non-paraxial cylindrical Gaussian beam are considered. The projections of the vector of the light force pressure exerted upon a dielectric cylinder of arbitrary and circular cross-section are expressed analytically. In particular, the pressure force is expressed through the coefficients of decomposition of the non-paraxial Gaussian beam into the cylindrical functions. Using numerical examples, a possibility to optically trap a circular-shaped cylinder in two oppositely directed Gaussian beams or a single non-paraxial Gaussian beam is demonstrated. [ABSTRACT FROM AUTHOR]

A novel method of designing a mirror surface to generate a directivity diagram represented as a vector function of one argument is presented. A general relationship for the mirror surface for an arbitrary illuminating beam wavefront is derived as an envelope of a parametric family of surfaces. Each surface in the family transforms the input beam into a beam with plane wavefront of desired direction. For the spherical illuminating beam the mirror surface is given as the envelope of the family of rotational paraboloids. The envelope is represented as a family of curves given by the intersections of paraboloids with circular cones of rays from the point source. [ABSTRACT FROM AUTHOR]

The reflection and transmission of tightly focused azimuthally, radially and linearly polarized electromagnetic wave beams with subwavelength spot size and wavefront curvature at a dielectric interface are investigated. For a given wavefront radius, the existence of the optimal radius of beam spot corresponding to a minimal reflectance and maximal transmittance is shown. Significant lateral shift in the transmitted intensity peak is revealed for strongly focused azimuthally and radially polarized beams that are normally incident to an interface. The reflection and transmission of transverse-electric- and transverse-magnetic- polarized extremely narrow wave beams which are obliquely incident on the dielectric interface is analysed. Disappearance of the Brewster angle and total internal reflection effects for the strongly focused beams are predicted. The change in beam profile after reflection and transmission for different polarizations, incident beam spots and incidence angles are analysed. [ABSTRACT FROM AUTHOR]

We have investigated experimentally the evolution of the intensity distribution of an initial off-axis vortex with topological charge 1 in a Laguerre–Gaussian background beam. It was found that the non-generic dislocation surface of the Laguerre–Gaussian beam destroyed and new vortices are created during propagation in agreement with calculations. The innermost vortex moves to the centre of the beam, in contrast to the other vortices, which propagate to the periphery. The motion of the innermost vortex is explained by a model employing phase and intensity gradients where the changes of the background beam during propagation are taken into account. [ABSTRACT FROM AUTHOR]

The dynamic evolution and stability of bright dissipative holographic solitons supported by protorefractive materials via two-wave mixing with a moving grating are investigated numerically. Results show that these solitons are stable relative to small perturbations. 'The state of such solitons can be easily controlled by adjusting some system parameters, such as the linear loss of the crystal and the frequency detuning between the pump beam and the self-trapping beam. Potential amplification in optical switches, repeaters or splitters is discussed. [ABSTRACT FROM AUTHOR]

Beam propagation factor (usually referred to as M 2 factor) and brightness of high-order symmetrical Laguerre-Gauss (LG) beams that diffract upon a hard-aperture are investigated. We demonstrate that a circular aperture is able to decrease the M 2 factor of a high-order symmetrical LG beam and also to enhance its brightness although losses are induced. [ABSTRACT FROM AUTHOR]

The Physical mechanism of the geometric phase in terms of angular momentum exchange is elucidated. It is argued that the geometric phase arising out of the cyclic changes in the transverse mode space of Gaussian light beams is a manifestation of the cycles in the momentum space of the light. The apparent non-conservation of orbital angular momentum in the spontaneous parametric down conversion for the classical light beams is proposed to be related to the geometric phase. [ABSTRACT FROM AUTHOR]