Showing papers on "Physical optics published in 2001"

Chapter 4 - Singular optics

Abstract: Singular optics is a branch of modern physical optics that involves a wide class of effects associated with the phase singularities in wave fields and with the topology of wave fronts. Optical singularities (optical vortices) exhibit some fundamental features absent in the "usual" fields with smooth wave fronts. Namely, optical vortices possess orbital angular momentum, topological charge for helical wave front of beams with well-defined direction of propagation. As a result, an interesting spatial evolution can be generated such as optical vortices "nucleation" and "annihilation" by pairs with participation of phase saddles, often called "optical chemistry." To study the structure of the circular edge dislocation, an isolated dark (zero-amplitude) ring is created within a light beam, with an analytical description of the field. A screw wave-front dislocation has a feature that the spatial structure of the wave front has the form of a helicoid around the dislocation axis. The chapter also describes reflection, refraction, interference and diffraction of OVs. Both frequency up- and down-conversion processes possess essential peculiarities for light beams with OVs. The chapter discusses the topology of wave fronts and vortex trajectories. Gouy phase shift in singular optics is also described in the chapter.

Optical trapping of dielectric particles in arbitrary fields.

Abstract: We present a new method to calculate trapping forces of dielectric particles with diameters D < or = lambda in arbitrary electromagnetic, time-invariant fields. The two components of the optical force, the gradient force and the scattering force, are determined separately. Both the arbitrary incident field and the scatterer are represented by plane-wave spectra. The scattering force is determined by means of the momentum transfer in either single- or double-scattering processes. Therefore the second-order Born series is evaluated and solved in the frequency domain by Ewald constructions. Numerical results of our two-force-component approach and an established calculation method are compared and show satisfying agreement. Our procedure is applied to investigate axial trapping by focused waves experiencing effects of aperture illumination and refractive-index mismatch.

Fermionic Linear Optics and Matchgates

Abstract: Fermionic linear optics is efficiently classically simulatable. Here it is shown that the set of states achievable with fermionic linear optics and particle measurements is the closure of a low dimensional Lie group. The weakness of fermionic linear optics and measurements can therefore be explained and contrasted with the strength of bosonic linear optics with particle measurements. An analysis of fermionic linear optics is used to show that the two-qubit matchgates and the simulatable matchcircuits introduced by Valiant generate a monoid of extended fermionic linear optics operators. A useful interpretation of efficient classical simulations such as this one is as a simulation of a model of non-deterministic quantum computation. Problem areas for future investigations are suggested.

Hybrid PO-MoM analysis of large axi-symmetric radomes

Abstract: Over the last three decades, intensive work has been done to develop techniques aimed at accurate and efficient analysis of antenna radome systems. Some applications involve radar operating in the millimeter wave range and for those cases the radome size can be on the order of one hundred wavelengths or so in length. For practical simulations of such large radomes, a hybrid physical optics-method of moments (PO-MoM) technique is presented for accurate and efficient analysis of electrically large radomes. The procedure combines the method of moments (MoM) for modeling the tip region of the dielectric radome and ray optics in conjunction with physical optics (PO) for treating the flatter smooth section of the radome. Calculated far-field patterns using the new technique agree well with measured data for a reflector antenna radiating in the presence of a large radome. The computational time for simulating the performance of a 46/spl lambda/ reflector in the presence of an 88/spl lambda/ long radome was a mere 4 h on a 233 MHz PC.

Stationary phase method application for the analysis of radiation of complex 3-D conducting structures

Abstract: The stationary phase method is used to calculate the radiation pattern of antennas on complex structures. Physical optics (PO) approximation has been applied for the induced currents. The problem is stated directly over the parametric surfaces used to model the geometry and no translation of geometrical formats is required. The integral comes from the contribution of certain points on the surface (specular, boundary and vertices) where the phase term of the integrand presents a stationary behavior. In general, the asymptotic integration behaves similar to the numerical one but being more efficient in execution time than the latter.

Using two models in optics: Students' difficulties and suggestions for teaching

Abstract: This paper focuses on difficulties linked to situations in physics involving two models: geometrical optics and wave optics. The starting point is an investigation of university-level students’ difficulties. Excerpts from textbooks are given, to illustrate potential difficulties. A content analysis is then presented, underlining two important features required for dealing with such situations: awareness of the status of the drawings, and the “backward selection” of paths of light. These features could provide some guidelines for the designing of innovative teaching strategies.

Multiresolution grid algorithm in the SBR and its application to the RCS calculation

Abstract: We present a fast algorithm to calculate the radar cross section (RCS) of electrically large targets using a shooting-and-bouncing rays (SBR) method. By applying multiresolution grid ray tubes, we accelerate the ray tracing in the SBR. The numerical results illustrate the accuracy and efficiency of our proposed algorithm. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 394–397, 2001.

Diffraction of short pulses with boundary diffraction wave theory.

Abstract: The diffraction of short pulses is studied on the basis of the Miyamoto-Wolf theory of the boundary diffraction wave, which is a mathematical formulation of Young's idea about the nature of diffraction. It is pointed out that the diffracted field is given by the superposition of the boundary wave pulse (formed by interference of the elementary boundary diffraction waves) and the geometric (direct) pulse (governed by the laws of geometrical optics). The case of a circular aperture is treated in details. The diffracted field on the optical axis is calculated analytically (without any approximation) for an arbitrary temporal pulse shape. Because of the short pulse duration and the path difference the geometric and the boundary wave pulses appear separately, i.e., the boundary waves are manifested in themselves in the illuminated region (in the sense of geometrical optics). The properties of the boundary wave pulse is discussed. Its radial intensity distribution can be approximated by the Bessel function of zero order if the observation points are in the illuminated region and far from the plane of the aperture and close to the optical axis. Although the boundary wave pulse propagates on the optical axis at a speed exceeding c, it does not contradict the theory of relativity.

Electromagnetic scintillation. I. Geometrical optics

Abstract: Electromagnetic scintillation describes the phase and amplitude fluctuations imposed on signals that travel through the atmosphere. These volumes provide a modern reference and comprehensive tutorial for this subject, treating both optical and microwave propagation. Measurements and predictions are integrated at each step of the development. This first volume deals with phase and angle-of-arrival measurement errors. These are accurately described by geometrical optics. Measured properties of tropospheric and ionospheric irregularities are reviewed first. Electromagnetic fluctuations induced by these irregularities are estimated for a wide range of applications and compared with experimental results in each case. These fluctuations limit the resolution of astronomical interferometers and large single-aperture telescopes. Synthetic-aperture radars and laser pointing/tracking systems are also limited by such effects. Phase errors ultimately limit the accuracy of laser metrology and GPS location. Similar considerations will become important as terrestrial and satellite communications move to higher frequencies. Scintillation measurements now provide an accurate and economical way to establish atmospheric properties. Amplitude and intensity fluctuations are addressed in the second volume. This volume will be of particular interest to astronomers, applied physicists and engineers developing instruments and systems at the frontier of technology. It also provides a unique reference for atmospheric scientists and scintillation specialists. It can be used as a graduate textbook and is designed for self-study. Extensive references to original work in English and Russian are provided.

Geometric Optics and Long Range Scattering for One-Dimensional Nonlinear Schrödinger Equations

Abstract: With the methods of geometric optics used in [2], we provide a new proof of some results of [10], to construct modified wave operators for the one-dimensional cubic Schrodinger equation. We improve the rate of convergence of the nonlinear solution towards the simplified evolution, and get better control of the loss of regularity in Sobolev spaces. In particular, using the results of [9], we deduce the existence of a modified scattering operator with small data in some Sobolev spaces. We show that in terms of geometric optics, this gives rise to a “random phase shift” at a caustic.

Uncertainties in interferometric measurements of radius of curvature

Abstract: The radius of curvature of spherical surfaces may be determined using the well-known radius, or optical, bench. In this method, a figure measuring interferometer is employed to identify the null positions at the center of curvature (confocal) and surface (cat's eye) of the test optic. A linear slide provides motion between these positions and one or more displacement transducers is used to record the displacement between the cat's eye and confocal positions and, hence, the radius of curvature. Measurements of a polished Zerodur sphere have been completed on the X-ray Optics Calibration Interferometer (XCALIBIR) using both Twyman-Green and Fizeau configurations. Mechanical measurements of the spherical artifact have also been completed using a coordinate measuring machine (CMM). Recorded disagreement between the individual transmission sphere measurements and CMM measurements under well-controlled environmental conditions is larger than the limits predicted from a traditional uncertainty analysis based on a geometric measurement model. Additional uncertainty sources for the geometric model, as well as a physical optics model of the propagation of light, are therefore suggested. The expanded uncertainty analysis is described.

Ray tracing technique and its verification for the analysis of highly multimode optical waveguides with rough surfaces

Abstract: A novel hybrid ray tracing technique for the analysis of signal propagation in highly multimode optical waveguides with rough surfaces and its verification in part is presented. The technique combines geometrical optics with a light scattering model, based on wave optics by applying a Monte Carlo method. While the light scattering model takes mode coupling caused by surface irregularities into account, the ray tracing technique provides the analysis of light propagation in highly multimode waveguides with arbitrary shapes. The verification is obtained by calculating wave propagation within a slab waveguide with rough surfaces applying the well known coupled power theory, which provides the power of the guided modes versus the axial coordinate of the waveguide. Therefore, the ray tracing results are transformed into the discrete waveguide modes in order to compare the results.

Radiometry and wide-angle wave fields III: partial coherence.

Abstract: The analogs of the generalized radiances introduced in two previous manuscripts [J. Opt. Soc. Am. A18, 902 (2001) and J. Opt. Soc. Am. A18, 910 (2001)] for fully coherent fields in two- and three-dimensional free space are given here for the case of partial coherence. These functions are exactly conserved along rays and are suitable for the description of fields with components propagating in any direction. Also defined here is a global measure of coherence, which can be expressed in terms of the new functions. The cases of radiation in a blackbody cavity and partially coherent focused waves are considered as examples.

Long-wave short-wave resonance for nonlinear geometric optics

Abstract: The aim of this paper is to study oscillatory solutions of nonlinear hyperbolic systems in the framework developed during the last decade by J.-L. Joly, G. Metivier, and J. Rauch. Here we focus mainly on rectification effects, that is, the interaction of oscillations with a mean field created by the nonlinearity. A real interaction can occur only under some geometric conditions described in [JMR1] and [L1] that are generally not satisfied by the physical models except in the 1-dimensional case. We introduce here a new type of ansatz that allows us to obtain rectification effects under weaker assumptions. We obtain a new class of profile equations and construct solutions for a subclass. Finally, the stability of the asymptotic expansion is proved in the context of Maxwell-Bloch-type systems.

Cross-polarized wave generation by effective cubic nonlinear optical interaction

Abstract: A new cubic nonlinear optical effect in which a linearly polarized wave propagating in a single quadratic medium is converted into a wave that is cross polarized to the input wave is observed in BBO crystal. The effect is explained by cascading of two different second-order processes: second-harmonic generation and difference frequency mixing.

Compact HMD optics based on multiplexed aberration-compensated holographic optical elements

Abstract: Head and helmet mounted displays (HMDs) can benefit greatly from new wide field-of-view, compact visor optics to project very high resolution (e.g., 5k X 4k) imagery. Physical Optics Corporation (POC) is developing novel, compact, lightweight wide field-of-view optics based on three-color multiplexed aberration-compensated holographic optical elements (MAC-HOEs). Taking advantage of the flexibility of holography, the HMD optics can be made compact using waveguide projection through the curved visor substrate, so that the see-through visor can have a wide field-of-view without large, bulky optical components. Using narrowband red-green-blue hologram multiplexing, MAC-HOEs can significantly reduce the chromatic and geometrical aberration introduced by conventional HOEs and refractive optics. In the initial phase of development, POC demonstrated the feasibility of the HMD optics through computer design and analysis, and by fabricating and demonstrating a MAC-HOE component.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Sequence of phase correction in multiconjugate adaptive optics.

Abstract: The way in which the sequence of phase correction impinges on performance in multiconjugate adaptive optics systems is described. When multiple phase modulators with different conjugate ranges are used, the conjugate images of the phase modulators in the atmosphere must be reimaged in the reverse order post focus, and adaptive phase correction applied in this sequence for perfect amplitude and phase cancellation. Performing the correction without relay optics results in residual amplitude and phase aberrations. It is shown, by Monte Carlo simulations of Fresnel propagation, that the effects of wave optical propagation become nonnegligible at visible wavelengths and for large air masses.

Scattering by a groove in a conducting plane-a PO-MoM hybrid formulation and wavelet analysis

Abstract: A novel method is presented to solve the two-dimensional (2-D) problem of scattering of an electromagnetic plane wave by a groove in a perfectly conducting infinite plane. In this method, the unknown induced current is expressed in terms of the known physical optics solution of the unperturbed problem of scattering by an infinite conducting plane plus a yet to be determined localized correction current placed in the vicinity of the groove. It is then shown that a good approximation of the induced current can be obtained using only a few dominant functions in the wavelet expansion of the correction current. Moreover, the same set of dominant wavelet functions serves the purpose of approximating the induced current at different angles of incidence. A numerical example demonstrates these various features of the proposed method of solution.

Visualization of optical phenomena caused by multilayer films based on wave optics

Abstract: This paper proposes a method for rendering objects coated with multilayer thin films, taking into consideration multiple reflection and refraction, interference, and absorption of light inside the films. The proposed method is based on wave optics, and it can accurately visualize the optical effects of multilayer films consisting of not only dielectric materials, but also metallic and semiconductive materials. Optical properties of a SiO2 film coating on a silicon base, and several kinds of multilayer films coating windowpanes, glasses, or teapots are visualized to demonstrate the usefulness of the proposed method.

Directions in Quantum Optics

Abstract: This collection of papers written by leading researchers reflects the forefront of research in the dynamic field of quantum optics. Topics covered include BEC, atomic optics, quantum information, cavity QED and quantum noise processes.

Improvement of the hybrid moment method–physical optics method through a novel evaluation of the physical optics operator

Abstract: This paper presents an alternative procedure for the evaluation of the physical optics (PO) contribution into a hybrid moment method–physical optics (MM–PO) code. The proposed formulation includes a linear interpolation of the phase over large triangular subdomains for the PO regions, where the radiated field can be analytically determined. This allows a drastic reduction of the computational cost, while maintaining or even improving the degree of accuracy. In this way, the scope of application of the MM–PO hybrid code is enhanced to larger problems in terms of wavelength. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 357–363, 2001.

Atom optics: Old ideas, current technology, and new results

Abstract: Atom optics is the coherent manipulation of the atomic matter waves originally postulated by the developers of quantum mechanics. These pioneers also proposed the use of stimulated light forces to manipulate particles. These ideas have been combined with current technology to produce the field of atom optics. This, in turn, has shed new light on old quantum problems like the which way problem and the origins of quantum decoherence. Bose Einstein condensates combine naturally with atom optics to produce new results such as the coherent amplification of matter waves. This review of atom optics traces these connections.

Nonlinear geometrical optics for oscillatory wave trains with a continuous oscillatory spectrum

Abstract: The frequency and the direction of propagation of an oscillatory wave train may be read on its oscillatory spectrum. Many works in geometrical optics allow the study of at most countable oscillatory spectra. In these works, the number of directions of propagation is therefore at most countable, while many physical effects would require a continuous infinity of directions of propagation. The goal of this paper is to make the nonlinear geometrical optics for wave trains with such a continuous oscillatory spectrum. This requires the introduction of new spaces, which are Wiener algebras associated to spaces of vector-valued measures with bounded total variation. We also make qualitative studies on the properties of wave trains with continuous oscillatory spectrum, and on the incidence of the nonlinearity on such oscillations. We finally suggest an application of the results of this paper to the study of both the spontaneous and the stimulated Raman scatterings.

A time-domain physical optics heuristic approach to passive intermodulation scattering

Abstract: Passive intermodulation (PIM) is a phenomenon which often arises at junctions between different materials. This may be a major issue in tightly packed antenna farms as those typically present on communication satellites. Here, an heuristic nonlinear extension to the time-domain physical optics (TD-PO) is proposed, to take into account electromagnetic scattering at intermodulated frequencies when such a junction is illuminated by two impinging electromagnetic fields at different frequencies. Simulation results are compared with measures to validate the model.

From monochromatic light diffraction to colour schlieren photography

Abstract: The early experiments of Hiedemann on light diffraction led to an understanding of many experimental aspects of the subject, and defined many topics for further investigation. The theory of Raman and Nath broadened the understanding and defined many concepts that were not apparent to the experimenter. Although this theory is basically correct, it has been revised and improved over the years. The transition between Raman-Nath and Bragg diffraction was illuminated by the definitions of Klein, Cook and Mayer. Initially, the main focus of many investigations was on light diffraction by ultrasonic waves because there are many aspects of the subject. Later, it was realized that this interaction is an ideal way to study wave phenomena generally since optical diffraction does not disturb the ultrasonic wave. The unique perspective provided by acousto-optic interactions has made this a useful tool. By imaging ultrasonic waves one can make detailed studies of ultrasonic wave interactions and apply the results to many other types of waves. With acousto-optics one can study evanescent waves, ultrasonic finite amplitude effects, Bragg diffraction, Bragg imaging, etc. The application to other systems makes this a truly formidable study. The development of modern optics has made possible the description and understanding of wave interactions that heretofore had been mysterious. This paper begins with a description of early experiments. Later, it deals with finite-amplitude effects, parametric oscillations, Bragg diffraction and Bragg imaging. The study of evanescent waves by schlieren photography is a special case. Some topics have been studied by theory and experiment; some still await an acoustical theory although an optical theory exists, along with acoustical verification. Contributions of many citizens of the USA are considered. The paper ends with the application of the modern concepts of spatial filtering and information content to the analysis of colour schlieren photography.

Shadow boundary incremental length diffraction coefficients applied to scattering from 3-D bodies

Abstract: Shadow boundary incremental length diffraction coefficients (SBILDCs) are high-frequency fields designed to correct the physical optics (PO) field of a three-dimensional (3-D) perfectly electrically conducting scatterer. The SBILDCs are integrated along the shadow boundary of the 3-D object to approximate the field radiated by the nonuniform shadow boundary current (the difference between the exact and PO currents near the shadow boundary). This integral is added to the PO field to give an approximation to the exact scattered field that takes into account both PO and nonuniform shadow boundary currents on the scatterer. Like other incremental length diffraction coefficients, any SBILDC is based on the use of a 2-D canonical scatterer to locally approximate the surface of the 3-D scatterer to which it is applied. Circular cylinder SBILDCs are, to date, the only SBILDCs that have been obtained in closed form. In this paper, these closed-form expressions are validated by applying them for the first time to a 3-D scatterer with varying radius of curvature-the prolate spheroid. The results obtained clearly demonstrate that for bistatic scattering the combined PO-SBILDC approximation is considerably more accurate than the PO field approximation alone.

Dyadic analysis of partially coherent submillimeter-wave antenna systems

Abstract: We describe a procedure for simulating the behavior of partially coherent submillimeter-wave antenna systems. The procedure is based on the principle that the second-order statistical properties of any partially coherent vector field can be decomposed into a sum of fully coherent, but completely uncorrelated, natural modes. Any of the standard electromagnetic analysis techniques-physical optics, geometrical theory of diffraction, etc.-can be used to propagate and scatter the modes individually, and the statistical properties of the total transformed field reconstructed at the output surface by means of superposition. In the case of modal optics-plane waves, Gaussian optics, waveguide mode matching, etc.-the properties of the field can be traced directly by means of scattering matrices. The overall procedure is of considerable value for calculating the behavior of astronomical instruments comprising planar and waveguide multimode bolometers, submillimeter-wave optical components, and large reflecting antennas.

Wave propagation in one-dimensional optical quasiperiodic systems.

Abstract: One-dimensional quasiperiodic optical systems are studied, using a Schrodinger-like equation with a potential V(x)=2lambda(1) cos x+2lambda(2) cos alphax as an approximation to the wave equation in the slowly-varying wave approximation. It is shown that small changes in the parameter alpha produce major changes in the band structure of the system. For certain values of alpha, the band structure consists of many "thin bands" and allows the possibility of dense multiplexing. The propagation of "noisy optical waves" that contain many frequencies with a thermal distribution is also studied with a thermodynamic model. Quantities like the thermodynamically averaged group velocity and the thermodynamically averaged inverse effective mass are introduced in order to quantify the complex relation between the frequency and wave vector in these systems.

Fast Physical Optics Simulations of the Multi-Beam Dual-Reflector Submillimeter-Wave Telescope on the ESA PLANCK Surveyor

Abstract: We present physical optics simulations of the multi-beam dual-reflector submillimeter-wave telescope on the ESA PLANCK surveyor designed for measuring the temperature anisotropies and polarization characteristics of the cosmic microwave background. The telescope is of a non-conventional Gregorian configuration, with two ellipsoidal reflectors providing a very large field of view at the focal plane where the array of 76 horn antennas feeding low-temperature detectors is located. We analyse the defocusing effects of the system, the polarization properties of the telescope, and the optical performance of the high-frequency channels based on special multi-moded horns operating at 545 and 857 GHz.