Showing papers in "Journal of Modern Optics in 1998"
TL;DR: In this paper, the basic physical ideas behind electromagnetically induced transparency (EIT) are elucidated and the relation of EIT to other processes involving laser-induced atomic coherence, such as coherent population trapping, coherent adiabatic population transfer and lasing without inversion, is discussed.
Abstract: The subject of electromagnetically induced transparency (EIT) is reviewed in this paper. Emphasis is placed on the experimental work reported in this field since 1990. Theoretical work is also covered, although it is not intended to review all the very numerous recent theoretical treatments on this topic. The basic physical ideas behind EIT are elucidated. The relation of EIT to other processes involving laser-induced atomic coherence, such as coherent population trapping, coherent adiabatic population transfer and lasing without inversion, is discussed. Experimental work is described covering the following topics: EIT with pulsed and continuous-wave sources, lasing without inversion, pulse propagation in a laser dressed medium and EIT in nonlinear optical processes. A full set of references and a bibliography are included.
892 citations
TL;DR: In this paper, a review of the role of surface and waveguide modes in photonic near interfaces is presented, including the importance of textured surfaces in providing large changes in the photonic mode density and coupling non-radiative modes to radiation.
Abstract: A review of fluorescence near interfaces is presented. Recent work that examines the role of photonic mode density in this process is surveyed and the underlying concepts discussed. The review includes an examination of the role of surface and waveguide modes, as well as non-radiative decay. The importance of textured surfaces in providing large changes in photonic mode density and in coupling non-radiative modes to radiation is highlighted. Indications are given for future areas of research and on how photonic mode density may influence optical processes other than fluorescence.
888 citations
TL;DR: In this article, a computer-generated hologram is used for the production of high-order multiringed Laguerre-Gaussian modes with specific azimuthal and radial indices.
Abstract: A computer-generated hologram is used for the production of high-order multiringed Laguerre–Gaussian modes. These holograms differ from those previously reported in that they have an additional circular discontinuity. The holograms are used in transmission and are designed to convert the fundamental Hermite–Gaussian laser mode into a Laguerre–Gaussian mode with specific azimuthal and radial indices. The optical efficiency exceeds 40% with a radial mode purity of approximately 80%.
279 citations
TL;DR: In this article, the axial trapping efficiency of optical tweezers was improved by using a Laguerre-Gaussian laser mode as the trapping beam for a wide range of particle sizes and sample cell depths.
Abstract: We demonstrate that the axial trapping efficiency in optical tweezers is improved by using a Laguerre-Gaussian laser mode as the trapping beam. For a wide range of particle sizes and sample cell depths, the laser power required with an l = 3 Laguerre-Gaussian mode is reduced by a factor of two compared with that of the fundamental mode. This is important for biological applications where a reduction in the laser power lessens the risk of damage to living samples.
114 citations
TL;DR: In this article, an accurate method for computing the elecromagnetic field distribution in lamellar gratings is proposed, which relies on the rigorous coupled-wave analysis provided accurate numerical results and avoids possible sources of artefacts due to permittivity discontinuities.
Abstract: In this paper, an accurate method for computing the elecromagnetic field distribution in lamellar gratings is proposed. The method that relies on the rigorous coupled-wave analysis provides accurate numerical results and avoids possible sources of artefacts due to permittivity discontinuities. Its performance is analysed through various lamellar grating cases, including dielectric and metallic materials, the visible and near-infrared (1–10 μm) regions of the spectrum. Special attention is placed on field singularities which are in general present at the grating wedges for transverse magnetic polarization.
113 citations
TL;DR: In this paper, the temporal evolution of holographic volume diffraction gratings is monitored for a range of illumination intensities in two ways: (i) by means of a multiple-exposure approach when intensity profiles of recording beams are uniform, many holographic exposures are necessary and each exposure is carried out for a particular value of the total illumination intensity.
Abstract: Recording of holographic volume diffraction gratings in Du Pont's photopolymer HRS-150 is studied theoretically and experimentally. Particular attention is paid to the dynamics of the recording process. The temporal evolution of holographic gratings is monitored for a range of illumination intensities in two ways: (i) by means of a multiple-exposure approach when intensity profiles of recording beams are uniform, many holographic exposures are necessary and each exposure is carried out for a particular value of the total illumination intensity; (ii) by means of a single-exposure approach when intensity profiles of recording beams are strongly Gaussian and a volume grating with spatially distributed diffraction efficiency arises, depending on a local (average) value of the total illumination intensity. The second approach proves to be a useful tool providing us very quickly with qualitative information about the dynamics of the recording process while the first one, which is much more time-consumi...
109 citations
TL;DR: In this paper, a method for reducing the decoherence of a quantum bit (qubit) is proposed, which is based on the photon-echo phenomenon in coherent optical transient.
Abstract: A useful method for reducing the decoherence of a quantum bit (qubit) is proposed, which is based on the photon-echo phenomenon in coherent optical transient. The decoherence of the qubit is caused by the dephasing coupling with a bosonic thermal reservoir. In the method, successive coherent π pulses are applied with very short pulse widths to reduce the decoherence. It is found that the decoherence of the qubit disappears at a certain time which can be controlled by appropriately choosing the pulse separation time and the number π pulses.
103 citations
TL;DR: In this article, the Fourier modal method (FMM) for anisotropic surface-relief gratings is reformulated using the correct Fourier factorization rules presented in an earlier paper by Li.
Abstract: By the use of the correct Fourier factorization rules presented in an earlier paper by Li the Fourier modal method (FMM) for anisotropic surface-relief gratings is reformulated. The newly formulated FMM converges much faster than the old formulation when the permittivity contrast in the grating groove region is large. Highly conducting lamellar gratings coated with anisotropic materials can now be analysed easily. In addition, a simple set of criteria are given for determining the energy propagation directions of the plane waves associated with the real solutions of the Booker quartic.
100 citations
TL;DR: In this paper, the modal theory of coherence is applied to partially coherent sources whose modes belong to the class of Laguerre-Gauss functions for which the Laguero polynomial has zero order.
Abstract: On the basis of the modal theory of coherence, we study partially coherent sources whose modes belong to the class of Laguerre-Gauss functions for which the Laguerre polynomial has zero order. Thes...
99 citations
TL;DR: In this paper, the photon statistics of weak light pulses emitted in the process of pulsed parametric downconversion were calculated and measured, and photon bunching was found as expected from a chaotic light source when viewed through a narrow-band filter.
Abstract: We calculate and measure the photon statistics of weak light pulses emitted in the process of pulsed parametric down-conversion. We find photon bunching as expected from a chaotic light source when viewed through a narrow-band filter.
90 citations
TL;DR: In this paper, the authors consider intermediate measurements which interpolate between these extremes and derive a general lower bound on the combination of errors and inconclusive results, and describe a family of measurement strategies which attains this limit.
Abstract: Any measurement strategy designed to discriminate between nonorthogonal quantum states will have a finite probability of yielding erroneous or inconclusive results. The lower bounds on these probabilities for conclusive and error-free strategies are given by the Helstrom and Ivanovic–Feres limits respectively. We consider intermediate measurements which interpolate between these extremes and derive a general lower bound on the combination of errors and inconclusive results. We also describe a family of measurement strategies which attains this limit.
TL;DR: An alternative set of eigensolutions of the paraxial wave equation to that of the ordinary Hermite-Gaussian modes is that ofThe so-called ‘elegant’ Hermite, Gaussian modes, from which the analogous elegant Laguerre-GaRussian modes are derived.
Abstract: An alternative set of eigensolutions of the paraxial wave equation to that of the ordinary Hermite-Gaussian modes is that of the so-called ‘elegant’ Hermite-Gaussian modes. The analogous elegant Laguerre-Gaussian modes are derived. The near- and far-field behaviours of the elegant Hermite-Gaussian and Laguerre-Gaussian modes are investigated. The similarity between the elegant Laguerre-Gaussian beams and the Bessel-Gaussian beams is discussed.
TL;DR: In this paper, the phase singularities of a Gaussian wave are studied in detail, and the geometrical sensitivity of the wave to L is shown to change when the waist expands by a few thousandths of a wavelength.
Abstract: For exact (i.e., non-paraxial) waves ψ representing freely propagating Gaussian beams in two and three dimensions, the patterns of phase singularities, that is zeros of ψ, are studied in detail. The zeros (points in two dimensions, and rings in three) are phase dislocations (optical vortices). The waves depend on a single parameter L, representing the radius of the waist of the beam. As L increases, pairs of dislocations interact and depart from the focal plane. Each such interaction comprises three events where the phase topology of ψ changes; each event is a reaction between the dislocations and associated phase saddles, conserving two topological quantum numbers. The same behaviour was predicted and observed by Karman et al. for beams truncated by apertures. The geometrical sensitivity of the wave to L is astonishing: changes in phase topology can occur when the waist expands by a few thousandths of a wavelength. The integral representing ψ is evaluated asymptotically, leading to a global expl...
TL;DR: In this article, the authors developed the theory of confocal microscopes imaging small scatterers and employed a full vectorial theory to treat the problem of scattering in high aperture systems as well as image formation in polarized light microscopy.
Abstract: In this paper we develop the theory of confocal microscopes imaging small scatterers. Since scattering is a polarization dependent phenomenon we employ a full vectorial theory to treat this problem. This approach permits us to consider both imaging in high aperture systems as well as image formation in polarized light microscopy. We extend previous theories by including effects of the finite sized detector apertures. Numerical examples are presented for the most important cases. The results of the full vectorial theory are compared with those obtained from low aperture paraxial theory.
TL;DR: In this article, a general formalism is presented to analyse chirality effects of second-harmonic generation and apply it to review known effects and to introduce new effects, which can be classified as achiral (allow for all isotropic surfaces) or chiral (only for chiral surfaces) independent of the details of the nonlinear light-matter interaction.
Abstract: Second-harmonic generation can be used to probe chiral properties of surfaces and thin films with in-plane isotropy. We present a general formalism to analyse such chiral effects and apply it to review known effects and to introduce new effects. The formalism is based on expanding the fundamental and second-harmonic fields in terms of their p- and s-polarized components. Each second-harmonic signal can then be described in terms of only three nonlinear coefficients, which are associated with the quadratic combinations of the fundamental-field components. The coefficients can be classified as achiral (allowed for all isotropic surfaces) or chiral (allowed only for chiral surfaces) independent of the details of the nonlinear light-matter interaction. The basic signatures of chirality are intensity-difference effects in which the efficiencies of second-harmonic generation are different for left- and right-hand circularly-polarized light or two orthogonal linear polarizations, for example. These effe...
TL;DR: In this article, the problem of identifying a Mueller matrix M through N = [Mtilde]GM was revisited, where G is the familiar Minkowski matrix diag and the tilde denotes matrix transposition.
Abstract: We revisit the problem of identifying a Mueller matrix M through N = [Mtilde]GM where G is the familiar Minkowski matrix diag (1, −1, −1, −1) and the tilde denotes matrix transposition. Using the standard methods of reduction of symmetric matrices (tensors) to their canonical forms in Minkowski space, we then show that there exist only two algebraically distinct types of Mueller matrices, which we call types I and II, and obtain the necessary and sufficient conditions for a Mueller matrix in terms of the eigenproperties of the associated N matrix. These conditions identify a Mueller matrix precisely and completely unlike the conditions derived earlier by Givens and Kostinski or by van der Mee. Observing that every Mueller matrix discussed hitherto in the literature is of the type I only, we construct examples of type-II Mueller matrices using the more familiar type-I (in fact pure Mueller) Mueller matrices. Further, we show that every G eigenvalue of an N matrix (see section 2 for a definition) i...
TL;DR: In this article, a high-speed camera is used to acquire a number of frames of the image of the object motion sequentially, and the magnitude of the in-plane displacement of the motion is extracted.
Abstract: Measurement of in-plane displacements of a diffuse object by observing the temporal fluctuation of the speckle pattern in a dual-beam illumination speckle interferometer is illustrated. To conceive the temporal changes the object is displaced in its plane continuously. A high-speed camera is used to acquire a number of frames of the image of the object motion sequentially. Through Fourier transformation and inverse Fourier transformation of the frames stacked together, the total phase is determined. Finally, the magnitude of the in-plane displacement of the object motion is extracted. The range of displacement that can be measured using this novel method lies between few microns and over 100 μm on the upper end. Theory together with experimental results are presented in this paper.
TL;DR: In this paper, the steady state population behavior in a laser driven V-type system has been analyzed and the effects of spontaneous emission-induced coherence and of the relative phase of the two coherent driving fields are considered in detail.
Abstract: The steady-state population behaviour in a laser driven V-type system has been analysed. The effects of spontaneous emission-induced coherence and of the relative phase of the two coherent driving fields are considered in detail. A large and unexpected population inversion is found on one of the optical transitions due to these coherent effects.
TL;DR: In this paper, a unified approach to the problem of optical decomposition of coherent light fields in terms of orthogonal bases with rotor or angular harmonics is presented. And the results of computer simulation are discussed.
Abstract: We take a unified approach to the problem of an optical decomposition of coherent light fields in terms of orthogonal bases with rotor or angular harmonics. Examples of such bases are given: functions describing diffraction-free beam (Bessel functions), circular Zernike polynomials and modal Gauss–Laguerre functions. We consider an iterative algorithm for the design of phase diffractive optical elements serving to decompose the coherent light field in terms of the mentioned bases. The results of computer simulation are discussed.
TL;DR: In this paper, formulae for important optical quantities of single layers with slightly randomly rough boundaries are derived by means of a generalized Rayleigh-Rice theory, and the theoretical results are illustrated by a numerical analysis.
Abstract: In this theoretical paper, formulae for important optical quantities of single layers with slightly randomly rough boundaries are derived by means of a generalized Rayleigh–Rice theory. Thus the formulae for the specular reflectances and ellipsometric parameters of the layers mentioned are presented. The theoretical results are illustrated by a numerical analysis. Practical features implied by this analysis to be relevant from the experimental point of view are introduced as well. Moreover, relations expressing the flux of scattered light are presented.
TL;DR: In this article, the authors investigated the transverse trapping force in laser tweezers in the presence of spherical aberration caused by the refractive-index mismatch between a cover slip and the water solution where particles are suspended.
Abstract: Transverse trapping force in laser tweezers is investigated in the presence of spherical aberration caused by the refractive-index mismatch between a cover slip and the water solution where particles are suspended. The transverse trapping efficiency is characterized in terms of the numerical aperture of a microscope objective and the thickness of a sample cell. It has been experimentally demonstrated that the spherical aberration can be compensated for by changing the effective tube length of an objective used for trapping. As a result, the transverse trapping efficiency can be improved by up to 20%. In principle, a further improvement in the trapping efficiency is possible if an objective of an infinitely-long tube length is used.
TL;DR: In this article, the extended boundary condition method for three-dimensional scattering problems is derived by using a system of magnetic and electric dipoles, a Mie potentials, and a lowest-order multipoles as complete systems of functions.
Abstract: Novel formulations of the extended boundary condition method for three-dimensional scattering problems are derived by using a system of magnetic and electric dipoles, a system of ‘Mie potentials’ and a system of lowest-order multipoles as complete systems of functions. The key step in these approaches is to use discrete sources located on auxiliary supports to guarantee the null-field condition for the total electric field and to generate the surface current densities.
TL;DR: In this paper, a non-paraxial nonlinear Schrodinger equation is derived and an exact soliton solution from which the paraxial soliton is recovered in the appropriate limit.
Abstract: In this paper, we propose the use of ultranarrow soliton beams in miniaturized nonlinear optical devices. We derive a nonparaxial nonlinear Schrodinger equation and show that it has an exact non-paraxial soliton solution from which the paraxial soliton is recovered in the appropriate limit. The physical and mathematical geometry of the non-paraxial soliton is explored through the consideration of dispersion relations, rotational transformations and approximate solutions. We highlight some of the unphysical aspects of the paraxial limit and report modifications to the soliton width, the soliton area and the soliton (phase) period which result from the breakdown of the slowly varying envelope approximation.
TL;DR: In this article, the effect of laser coherence length on the performance of continuous-wave coherent laser radar (lidar) is examined, and different laser line-broadening mechanisms are considered, including phase diffusion and jitter.
Abstract: The effect of laser coherence length on the performance of continuous-wave coherent laser radar (lidar) is examined. A laboratory lidar investigation using semiconductor lasers with linewidths of the order of 1 MHz has been carried out for ranges much shorter than, comparable with and much longer than the laser coherence length (about 50m). The signal strength, spectrum and fluctuation statistics are all shown to be sensitive to the various effects resulting from limited laser coherence. Different laser line-broadening mechanisms are considered, including phase diffusion and jitter, and the fundamental difference between single- and multiple-mode sources is examined. Limited laser coherence is also shown to give rise to an excess noise contribution, and this can be severely detrimental to the lidar system performance.
TL;DR: In this article, Lohmann-coded binary-phase diffractive elements with restricted amplitude recording are fabricated by electron beam lithography and reactive ion etching, and the experimental results are in good agreement with theory.
Abstract: Transversally sharply structured optical fields are discussed, which rotate upon propagation without any lateral expansion of the intensity profile. Finite-aperture approximations of such fields, realizable with phase-only and complex-amplitude recording, are demonstrated. Recording of at least some of the amplitude information (rather than neglecting it completely) is shown to improve the field quality considerably, in particular close to the element. Lohmann-coded binary-phase diffractive elements with restricted amplitude recording are fabricated by electron beam lithography and reactive ion etching. The experimental results are in good agreement with theory.
TL;DR: In this paper, it was shown that every Mueller matrix M = L 2 KL 1 where L 1 and L 2 are orthochronous proper Lorentz matrices and K is a canonical Mueller matrix having only two different forms.
Abstract: We show that every Mueller matrix, that is a real 4 × 4 matrix M which transforms Stokes vectors into Stokes vectors, may be factored as M = L 2 KL 1 where L 1 and L 2 are orthochronous proper Lorentz matrices and K is a canonical Mueller matrix having only two different forms, namely a diagonal form for type-I Mueller matrices and a non-diagonal form (with only one non-zero off-diagonal element) for type-II Mueller matrices. Using the general forms of Mueller matrices so derived, we then obtain the necessary and sufficient conditions for a Mueller matrix M to be Jones derived. These conditions for Jones derivability, unlike the Cloude conditions which are expressed in terms of the eigenvalues of the Hermitian coherency matrix T associated with M, characterize a Jones-derived matrix M through the G eigenvalues and G eigenvectors of the real symmetric N matrix N = [Mtilde]GM associated with M. Appending the passivity conditions for a Mueller matrix onto these Jones-derivability conditions, we then...
TL;DR: In this paper, a high power Nd:glass laser using chirped pulse amplification was used to obtain peak intensities of 1019 W cm2 with a 3 times diffraction limited beam.
Abstract: Peak intensities of 1019 W cm2 have been reliably obtained from a high power Nd:glass laser using chirped pulse amplification. An Additive Pulse Modelocked oscillator incorporating diode pumped Nd:LMA was used to generate the sub-picosecond pulse. The focal spot intensity distribution has been characterized in detail showing a three times diffraction limited beam.
TL;DR: In this article, a detailed study of the optical dielectric function of optically thick TiN x films using grating coupling of radiation to surface plasmon-polaritons is presented.
Abstract: This work presents the first detailed study of the optical dielectric function of optically thick TiN x films using grating coupling of radiation to surface plasmon-polaritons. Angle-dependent reflectivities are obtained in the wavelength range 500–875 nm and by comparison with grating modelling theory, we determine both the imaginary and the real parts of the dielectric function. This method provides an alternative to traditional characterization techniques (e.g. Kramers-Kronig analysis) that may require additional information about film thickness, or the sample's optical properties in other parts of the electromagnetic spectrum. We have fitted the determined dielectric function to a model based on a combination of interband absorptions and free-electron response evaluating both the plasma energy and the relaxation time.
TL;DR: In this paper, the Berry phase for light was calculated from the Majorana picture of a spin system and the direction of propagation of light with fixed propagation direction, and the result accords with the quantum spin-1 formula of Bouchiat and Gibbons, and with the prescription for finding the geometric phase of light given by Bhandari.
Abstract: A natural geometric representation of the polarization of light with fixed propagation direction is a dot on a sphere in an abstract space: the Poincare sphere. If the direction of propagation is also included as a variable, a different description, given here, is natural. It is taken from quantum mechanics (from the Majorana picture of a spin system), spin one in the case of light. It characterizes polarized light by two dots on a unit sphere in the real space of directions (i.e. by two unit vectors). The direction of propagation is their bisector (or its reverse). Projecting the two dots onto the plane perpendicular to this direction gives the two foci of the polarization ellipse (which lies in this plane and has a unit semimajor axis). As an application of this picture the geometric Berry phase for light is calculated. The result accords with the quantum spin-1 formula of Bouchiat and Gibbons, and with the prescription for finding the geometric phase for light given by Bhandari.
TL;DR: In this article, the authors apply a new formalism to calculate the emission of light from sheared dielectric surfaces, where surface roughness with short period components reduces the extreme demands on velocity so that, for atomic-scale roughness, shear velocities as small as 104 ms−1 will result in light emission.
Abstract: We apply a new formalism to calculating emission of light from sheared dielectric surfaces. When the surfaces are smooth, the emission of light requires extreme velocities, but introducing surface roughness with short-period components reduces the extreme demands on velocity so that, for atomic-scale roughness, shear velocities as small as 104 ms−1 will result in light emission. Some order-of-magnitude estimates are given.