Showing papers on "Light field published in 1992"
TL;DR: The position of an atom passing through a standard light wave is localized by making a quadrature phase measurement on the light field, which can be thought of as the creation of a virtual slit for the atom by the field measurement.
Abstract: The position of an atom passing through a standard light wave is localized by making a quadrature phase measurement on the light field. This localization can be thought of as the creation of a virtual slit (or slits) for the atom by the field measurement. Diffraction and interference behavior may be observed in the far field.
177 citations
TL;DR: In this paper, it is shown that a new type of instability of a light field in a dissipative medium (spatiotemporal instability) can be observed by controlling the spatial scale and the topology of the transverse interactions of light fields in a medium with cubic nonlinearity.
Abstract: It is shown that a new type of instability of a light field in a dissipative medium (spatiotemporal instability, which causes the generation of new types of nonlinear light wave) can be observed by controlling the spatial scale and the topology of the transverse interactions of light fields in a medium with cubic nonlinearity. The excitation conditions for optical reverberators, rotating helical waves, and various dissipative structures are experimentally determined. Transformations and interactions of the structures lead to optical turbulence in both space and time. Physical interpretation of these phenomena is based on the parabolic equation for the nonlinear phase shift. It is found that this theoretical model allows one not only to obtain the excitation conditions but to investigate thoroughly such phenomena as hysteresis and nonlinear interactions of structures.
141 citations
TL;DR: The key idea is that an atom trapped in a minimum of the potential of the dipole forces is subject to a weaker-than-average damping, and therefore tends to boil out of the trap.
Abstract: We describe a numerical implementation of our semiclassical laser-cooling theory [J. Javanainen, Phys. Rev. A 44, 5857 (1991)] for an arbitrary multilevel atom and light field. There is satisfactory agreement between experiments and temperatures obtained from Langevin-equation simulations of the motion of an atom subject to light-pressure force and the accompanying diffusion in three-dimensional (3D) optical molasses in which there are three orthogonal pairs of counterpropagating waves with a common linear polarization for the two beams in a pair, but orthogonal polarizations between the pairs. However, the velocity distribution of the atoms is anisotropic and may deviate strongly from a Gaussian, heterodyne spectra may have a sideband, and the atomic density may be a maximum at the maximum of the potential of the dipole forces of the molasses beams. Subsequent velocity-linearized analysis of atomic damping and diffusion shows that the damping tensor may have a negative eigenvalue corresponding to heating in large regions of space, even though the light is red tuned for cooling. It is also found that the position-averaged damping and diffusion tensors make a poor predictor of the temperature obtained in Langevin-equation simulations and real experiments. Based on additional simulations of a simple 1D model, we formulate a hypothesis that connects our findings. The key idea is that an atom trapped in a minimum of the potential of the dipole forces is subject to a weaker-than-average damping, and therefore tends to boil out of the trap.
38 citations
TL;DR: In this article, a method for laterally manipulating the morphology of a thin film is presented, which uses the force exerted by light to deflect neutral atoms in an atomic beam during deposition.
Abstract: A new method for laterally manipulating the morphology of a thin film is presented, which uses the force exerted by light to deflect neutral atoms in an atomic beam during deposition. We have evaluated the dependence of the thickness of a thin metal film on the frequency, intensity, and the spatial structure of the light field, and find that the stimulated component of the force is suitable for laterally organizing atoms from centimeter to submicron dimensions.
38 citations
TL;DR: In this article, the results of numerical calculations or simple evaluations of relevant nonlinear susceptibilities for some atoms are presented in discussions of particular physical effects, such as nonlinear light scattering (three-photon scattering, harmonic generation), the effects of the field-induced optical anisotropy in an atomic gas and also the new nonlinear optical phenomena caused by dissipation of light energy in the medium or by nonstationary effects (the pulse spectral width) are considered on the basis of the developed formalism.
36 citations
Patent•
19 Jun 1992
TL;DR: In this article, a grid coupler is used for the selective detection of substances in chemical, biochemical and biological measuring samples by the determination of changes in the effective refractive index of an executed mode.
Abstract: The invention describes a process for the selective detection of substances in chemical, biochemical and biological measuring samples (13) by the determination of changes in the effective refractive index of an executed mode (16) with the aid of a grid coupler (10). The essential feature of the invention is that a grid (4) of the grid coupler (10) is illuminated by a fanshaped field of light (9), a mode (16) is excited and emitted virtually as a plane wave (17) owing to weak coupling, a position-sensitive detector (7) is in the light field (9) of a diffraction order and thus the shift in a bright spot of light (12) formed by the emitted light field (17) is measured.
14 citations
TL;DR: In this article, the effects of coherence and interference in light-matter systems are treated using a novel causality preserving density matrix formulation that operates in a mixed time-frequency domain and applies to quantum as well as classical systems.
11 citations
TL;DR: In this paper, the light field formed by focused laser beam scattering on moving and fixed surfaces is investigated and specific features of partially developed speckle-field dynamics are also analyzed.
6 citations
TL;DR: Of all the nonlinear terms in the model, the one describing the light shift can be singled out as responsible for the chaotic behavior and allows an intuitive understanding of the onset of chaos as a result of the interaction between spin precession and light shift.
Abstract: The interaction of spin-1/2 atoms in an optical resonator with a near-resonant cw light field and an external static magnetic field gives rise to self-sustained spin precession This entails a modulation on the transmitted light at roughly the Larmor frequency We show that under suitable conditions this oscillation can become irregular A detailed analysis reveals a deterministically chaotic process Dimensions, entropies, and Lyapunov exponents are determined; cross-checks demonstrate their mutual consistency To describe the observed dynamics, a three-dimensional model is presented that resembles the well-known Bloch equations Numerical simulations compare well with the experimental results Of all the nonlinear terms in the model, the one describing the light shift can be singled out as responsible for the chaotic behavior This allows an intuitive understanding of the onset of chaos as a result of the interaction between spin precession and light shift
5 citations
5 citations
Patent•
02 Nov 1992
TL;DR: In this article, the authors proposed a comparison check method to prevent the wrong detection of defect in a semiconductor wafer or a printed board from occurring due to a pattern formation state difference between two patterns to compare in a comparison-check method where the semiconductor or printed board is visually inspected.
Abstract: PURPOSE:To prevent the wrong detection of defect in a semiconductor wafer or a printed board from occurring due to a pattern formation state difference between two patterns to compare in a comparison check method where a semiconductor wafer or a printed board is visually inspected. CONSTITUTION:Two patterns imaged through light field illumination are compared with each other and binarized and a logical product of a light field binary image signal b detected making a defect part 'H' level and a dark field painting image signal d which makes only a prescribed region 'H' level out of a dark field image signal c imaged through dark field illumination is obtained. An exclusive logical sum of the logical product signal e and the light field binary image signal b is obtained, whereby defects detected in a part other than a region where a pattern formation state difference occurs are judged true defects.
31 Dec 1992
TL;DR: In this article, it was demonstrated that Fraunhofer lines in the solar spectrum will be filled in by inelastic scattering in the ocean, i.e., by measuring ij, the relative contributions of elastic and inlastic processes to the light field can be deduced.
Abstract: It is demonstrated that Fraunhofer lines in the solar spectrum will be filled in by inelastic scattering in the ocean. The relative depth of a Fraunhofer line, ij, defined as the ratio of the irradiance at the center of the Fraunhofer line to the background continuum, can then be used to measure the amount of inelastic scattering in the light field,i.e., by measuring ij, the relative contributions of elastic and inelastic processes to the light field can be deduced. An oceanographic instrument was developed to measure in-sifti inelastic scattering in the ocean. It utilizes a 1 m monochrometer, a CCD camera, and two irradiance collectors with a fiber optic light guide. Results of preliminaryfield measurements are presented and discussed. 1. INTRODUCTION Oceanic inelastic processes are increasingly being postulated as important sources in the underwater light field butuntil now no direct measurements of these processes in ambient light conditions have been reported.It has been demonstrated, theoretically, that Raman scattering can play a significant role in radiative transfer in
TL;DR: A fast and accurate method to determine the alignment of the diagnostic x-ray and light fields was developed that agrees with the corresponding results of the film-based procedure.
Abstract: A fast and accurate method to determine the alignment of the diagnostic x-ray and light fields was developed. Following the exposure, the boundaries of an x-ray field are determined by a custom-built x-ray field position detector and indicated by light-emitting diodes. The alignment of the supposed and the actual x-ray fields agree (within +/- 2 mm) with the corresponding results of the film-based procedure.
01 Apr 1992
TL;DR: A rotor filter is a phase optical element whose complex transmission function argument depends in a linear fashion upon the polar angle as discussed by the authors, and has been applied to optically differentiating the coherent light fields, possessing a rotational symmetry.
Patent•
05 Oct 1992
TL;DR: In this article, the authors proposed to expand the wavelength changing width of a variable wavelength semiconductor laser and improve the light output of the laser by spatially separating electrons and holes from each other.
Abstract: PURPOSE:To expand the wavelength changing width of a variable wavelength semiconductor laser and improve the light output of the laser by spatially separating electrons and holes from each other to a position where the light field is strong and another position where the light field is weak, respectively, and suppressing the increase of light absorption loss when the laser is operated under a variable wavelength condition. CONSTITUTION:A high carrier concentration layer 13 and low carrier concentration layer 14 are provided in a tuning layer 10 and a potential distribution is generated in the layer 10 by changing the carrier concentration in the layer 10. Because of the potential distribution, injected electrons and holes are spatially separated from each other. By constituting the carrier concentration distribution in the layer 10 so that the electrons can be distributed at a position where the light field is strong and the holes can be distributed at another position where the light field is weak, the increase of light absorption loss is reduced when the laser is operated under a variable wavelength condition and, as a result, the wavelength changing width of the laser can be expanded and the light output of the laser can be improved.
01 Sep 1992
TL;DR: In this article, the authors proposed using signal wavelengths within the reduced solar background provided by Fraunhofer lines to improve the performance of underwater optical communications in the upper ocean by using an additional light field.
Abstract: : Daytime performance of underwater optical communications in the upper ocean is limited by solar background To enhance performance, numerous researchers have proposed using signal wavelengths within the reduced solar background provided by Fraunhofer lines The perfor- mance improvement (references 1 and 2) gained by operating in a Fraunhofer line can be significant and, at some wavelengths, approaches an order of magnitude in signal-to-noise ratio However, recent work in optical oceanography suggests the presence of an "additional" light field (references 3-7) in the upper ocean The effect of an increased light field could significantly reduce (potentially eliminate) the absorption depth of Fraunhofer lines and reduce their solar-rejection benefits to optical communications For a number of years, optical oceanographers have measured abnormally low values for oceanic diffuse attenuation coefficients (K); and in certain cases, these values have been lower (references 8-12) than those for molecular water These abnormally low values of K indicate the presence of more light at depth than for the case of molecular water The increased light level has been suggested to result from internal-radiant emission caused by an inelastic (Raman) scattering process This action produces a wavelength-shifted band of light (references 3-7) with a mean frequency shift of 3357 /cm In other words, Raman scattering causes solar irradiance from shorter wavelengths to be wavelength-shifted to longer wavelengths, thus increasing ambient light at the longer wavelengths The result of this process should be more apparent in the "green" spectral region (reference 13) due to the transmission characteristics of seawater
13 Apr 1992
TL;DR: In this article, the authors studied the deflection of an atomic system with a resonant multilevel energy structure in classical and quantized wave light fields and showed that the shape of the momentum distribution is sensitive to the energy level structure, whereas its moments are not.
Abstract: We study the deflection of an atomic system with a resonant multilevel energy structure in classical and quantized wave light fields. We obtain that the shape of the momentum distribution is very sensitive to the energy level structure, whereas its moments are not. Comparison with a two-level case is made.
TL;DR: In this paper, a new approach to the description of the correlated emission laser gyroscope (holographic laser) is presented which is based on transformation between different representations of the light field inside the cavity.
TL;DR: The idea of the broken symmetry, which is applied to describe phase transition phenomena in condensed matter, is introduced into quantum optics to identify the state of a light field and investigate its time evolution as discussed by the authors.
Abstract: The idea of the broken symmetry, which is applied to describe phase transition phenomena in condensed matter, is introduced into quantum optics to identify the state of a light field and investigate its time evolution.
01 Jan 1992
TL;DR: In this paper, the authors proposed a coherent scattering of atomic beams by travelling and standing laser light waves is one of the key elements in the optical realization of a beam splitter and mirror in wave matter interferometry with atoms.
Abstract: Deflection of atoms by laser light has been the subject of various theoretical and experimental investigations during the last couple of years.1–6 For sufficiently short interaction times of the atom with the radiation field spontaneous emission can be neglected during excitation and the scattering process becomes coherent.2 Thus the wavepacket of a single atom incident on a light wave will be transformed by the radiative interaction into a superposition of product states of internal atomic levels and center of mass wavepackets; according to the momentum transfer by the light field these wavepackets will propagate into different directions and finally separate, forming a macroscopic superposition of quantum states. Apart from the intrinsic interest in the study of effects of macroscopic atomic superposition states, coherent scattering of atomic beams by travelling and standing laser light waves is one of the key elements in the optical realization of a beam splitter and mirror in wave matter interferometry with atoms7–13 (see also Refs. 14–16).
01 Jan 1992
TL;DR: Tan, Walls and Collett as discussed by the authors proposed an experiment in which only a single photon is involved and not a correlated photon pair in which two photons maintained their mutual quantum mechanical correlations even when spatially separated.
Abstract: We shall describe two novel quantum effects which can be realized in optics The first describes a proposal by Tan, Walls and Collett1 of an experiment which demonstrates the nonlocality of a single photon It differs from all other experiments and proposals on nonlocality in that only a single photon is involved and not a correlated photon pair In previous experiments two photons maintained their mutual quantum mechanical correlations even when spatially separated In the proposed experiment a single photon influences two spatially separated detectors The photon is incident on a beam splitter after which the photon may follow either of two routes to detectors which include a homodyne measurement of the photons quadrature phase The light field after the beam splitter may be described as an entangled state of one photon with the vacuum Nonclassical features in the coincidence rate between the two detectors are predicted Under certain conditions Bell’s inequalities may also be shown to be violated