Showing papers on "Physical optics published in 2009"

Optics and interferometry with atoms and molecules

Abstract: The development of wave optics for light brought many new insights into our understanding of physics, driven by fundamental experiments like the ones by Young, Fizeau, Michelson-Morley and others. Quantum mechanics, and especially the de Broglie’s postulate relating the momentum p of a particle to the wave vector k of an matter wave: k = 2 λ = p/ℏ, suggested that wave optical experiments should be also possible with massive particles (see table 1), and over the last 40 years electron and neutron interferometers have demonstrated many fundamental aspects of quantum mechanics [1].

Quadriwave lateral shearing interferometry for quantitative phase microscopy of living cells

Abstract: Phase imaging with a high-resolution wavefront sensor is considered. This is based on a quadriwave lateral shearing interferometer mounted on a non-modified transmission white-light microscope. The measurement technology is explained both in the scope of wave optics and geometrical optics in order to discuss its implementation on a conventional microscope. In particular we consider the effect of a non spatially coherent source on the phase-image signal-to-noise ratio. Precise measurements of the phase-shift introduced by microscopic beads or giant unilamellar vesicles validate the principle and show the accuracy of the methods. Diffraction limited images of living COS-7 cells are then presented, with a particular focus on the membrane and organelle dynamics.

Engineering nonlinearities in nanoscale optical systems: physics and applications in dispersion-engineered silicon nanophotonic wires

Abstract: The nonlinear optics of Si photonic wires is discussed. The distinctive features of these waveguides are that they have extremely large third-order susceptibility χ(3) and dispersive properties. The strong dispersion and large third-order nonlinearity in Si photonic wires cause the linear and nonlinear optical physics in these guides to be intimately linked. By carefully choosing the waveguide dimensions, both linear and nonlinear optical properties of Si wires can be engineered. We review the fundamental optical physics and emerging applications for these Si wires. In many cases, the relatively low threshold powers for nonlinear optical effects in these wires make them potential candidates for functional on-chip nonlinear optical devices of just a few millimeters in length; conversely, the absence of nonlinear optical impairment is important for the use of Si wires in on-chip interconnects. In addition, the characteristic length scales of linear and nonlinear optical effects in Si wires are markedly different from those in commonly used optical guiding systems, such as optical fibers or photonic crystal fibers, and therefore guiding structures based on Si wires represent ideal optical media for investigating new and intriguing physical phenomena.

Wigner distributions and how they relate to the light field

Abstract: In wave optics, the Wigner distribution and its Fourier dual, the ambiguity function, are important tools in optical system simulation and analysis. The light field fulfills a similar role in the computer graphics community. In this paper, we establish that the light field as it is used in computer graphics is equivalent to a smoothed Wigner distribution and that these are equivalent to the raw Wigner distribution under a geometric optics approximation. Using this insight, we then explore two recent contributions: Fourier slice photography in computer graphics and wavefront coding in optics, and we examine the similarity between explanations of them using Wigner distributions and explanations of them using light fields. Understanding this long-suspected equivalence may lead to additional insights and the productive exchange of ideas between the two fields.

Single-scattering properties of triaxial ellipsoidal particles for a size parameter range from the Rayleigh to geometric-optics regimes.

Abstract: The single-scattering properties of randomly oriented triaxial ellipsoids with size parameters from the Rayleigh to geometric-optics regimes are investigated. A combination of the discrete dipole approximation (DDA) technique and an improved geometric optics method (IGOM) is applied to the computation of ellipsoidal particle scattering properties for a complete range of size parameters. Edge effect contributions to the extinction and absorption efficiencies are included in the present IGOM simulation. It is found that the extinction efficiency, single-scattering albedo, and asymmetry factor computed from the DDA method for small size parameters smoothly transition to those computed from the IGOM for moderate-to-large size parameters. The phase matrix elements computed from these two methods are also quite similar when size parameters are larger than 30. Thus, the optical properties of ellipsoidal particles can be computed by combing the DDA and the IGOM for small-to-large size parameters. Furthermore, we also examine the applicability of the ellipsoid model to the simulation of the scattering properties of realistic aerosol particles by comparing the theoretical and experimental results for feldspar aerosols. It is shown that the ellipsoid model is better than the commonly used spheroid model for simulating dust particle optical properties, particularly, their polarization characteristics, realistically.

Conical diffraction and Bessel beam formation with a high optical quality biaxial crystal

Abstract: The manipulation of a Gaussian laser beam using conical diffraction in a high optical quality biaxial crystal of KGd(WO4)2 has been examined in detail with emphasis on the experimental techniques involved and intuitive explanations of the notable features. Two different optical arrangements were used to form the Pogendorff double-ring light pattern in the focal image plane. The formation of both diverging and non-diverging zeroth and first order Bessel beams was investigated. The various intensity distributions and polarization properties were measured and compared with the predictions of well-established theory.

Applied Digital Optics: From Micro-optics to Nanophotonics

Abstract: About the Authors. Foreword by Professor Joseph Goodman. Foreword by Professor Trevor Hall. Acknowledgments. Acronyms. Introduction . Why a Book on Digital Optics? Digital versus Analog. What are Digital Optics? The Realm of Digital Optics. 1 From Refraction to Diffraction . 1.1 Refraction and Diffraction Phenomena. 1.2 Understanding the Diffraction Phenomenon. 1.3 No More Parasitic Effects. 1.4 From Refractive Optics to Diffractive Optics. 1.5 From Diffractive Optics to Digital Optics. 1.6 Are Diffractives and Refractives Interchangeable Elements? 2 Classification of Digital Optics 2.1 Early Digital Optics. 2.2 Guided-wave Digital Optics. 2.3 Free-space Digital Optics. 2.4 Hybrid Digital Optics. 3 Guided-wave Digital Optics 3.1 From Optical Fibers to Planar Lightwave Circuits (PLCs). 3.2 Light Propagation in Waveguides. 3.3 The Optical Fiber. 3.4 The Dielectric Slab Waveguide. 3.5 Channel Waveguides. 3.6 PLC In- and Out-coupling. 3.7 Functionality Integration. 4 Refractive Micro-optics 4.1 Micro-optics in Nature. 4.2 GRIN Lenses. 4.3 Surface-relief Micro-optics. 4.4 Micro-optics Arrays. 5 Digital Diffractive Optics: Analytic Type. 5.1 Analytic and Numeric Digital Diffractives. 5.2 The Notion of Diffraction Orders. 5.3 Diffraction Gratings. 5.4 Diffractive Optical Elements. 5.5 Diffractive Interferogram Lenses. 6 Digital Diffractive Optics: Numeric Type. 6.1 Computer-generated Holograms. 6.2 Designing CGHs. 6.3 Multiplexing CGHs. 6.4 Various CGH Functionality Implementations. 7 Digital Hybrid Optics 7.1 Why Combine Different Optical Elements? 7.2 Analysis of Lens Aberrations. 7.3 Improvement of Optical Functionality. 7.4 The Generation of Novel Optical Functionality. 7.5 Waveguide-based Hybrid Optics. 7.6 Reducing Weight, Size and Cost. 7.7 Specifying Hybrid Optics in Optical CAD/CAM. 7.8 A Parametric Design Example of Hybrid Optics via Ray-tracing Techniques. 8 Digital Holographic Optics 8.1 Conventional Holography. 8.2 Different Types of Holograms. 8.3 Unique Features of Holograms. 8.4 Modeling the Behavior of Volume Holograms. 8.5 HOE Lenses. 8.6 HOE Design Tools. 8.7 Holographic Origination Techniques. 8.8 Holographic Materials for HOEs. 8.9 Other Holographic Techniques. 9 Dynamic Digital Optics 9.1 An Introduction to Dynamic Digital Optics. 9.2 Switchable Digital Optics. 9.3 Tunable Digital Optics. 9.4 Reconfigurable Digital Optics. 9.5 Digital Software Lenses: Wavefront Coding. 10 Digital Nano-optics 10.1 The Concept of 'Nano' in Optics. 10.2 Sub-wavelength Gratings. 10.3 Modeling Sub-wavelength Gratings. 10.4 Engineering Effective Medium Optical Elements. 10.5 Form Birefringence Materials. 10.6 Guided Mode Resonance Gratings. 10.7 Surface Plasmonics. 10.8 Photonic Crystals. 10.9 Optical Metamaterials. 11 Digital Optics Modeling Techniques . 11.1 Tools Based on Ray Tracing. 11.2 Scalar Diffraction Based Propagators. 11.3 Beam Propagation Modeling (BPM) Methods. 11.4 Nonparaxial Diffraction Regime Issues. 11.5 Rigorous Electromagnetic Modeling Techniques. 11.6 Digital Optics Design and Modeling Tools Available Today. 11.7 Practical Paraxial Numeric Modeling Examples. 12 Digital Optics Fabrication Techniques. 12.1 Holographic Origination. 12.2 Diamond Tool Machining. 12.3 Photo-reduction. 12.4 Microlithographic Fabrication of Digital Optics. 12.5 Micro-refractive Element Fabrication Techniques. 12.6 Direct Writing Techniques. 12.7 Gray-scale Optical Lithography. 12.8 Front/Back Side Wafer Alignments and Wafer Stacks. 12.9 A Summary of Fabrication Techniques. 13 Design for Manufacturing. 13.1 The Lithographic Challenge. 13.2 Software Solutions: Reticle Enhancement Techniques. 13.3 Hardware Solutions. 13.4 Process Solutions. 14 Replication Techniques for Digital Optics. 14.1 The LIGA Process. 14.2 Mold Generation Techniques. 14.3 Embossing Techniques. 14.4 The UV Casting Process. 14.5 Injection Molding Techniques. 14.6 The Sol-Gel Process. 14.7 The Nano-replication Process. 14.8 A Summary of Replication Technologies. 15 Specifying and Testing Digital Optics. 15.1 Fabless Lithographic Fabrication Management. 15.2 Specifying the Fabrication Process. 15.3 Fabrication Evaluation. 15.4 Optical Functionality Evaluation. 16 Digital Optics Application Pools. 16.1 Heavy Industry. 16.2 Defense, Security and Space. 16.3 Clean Energy. 16.4 Factory Automation. 16.5 Optical Telecoms. 16.6 Biomedical Applications. 16.7 Entertainment and Marketing. 16.8 Consumer Electronics. 16.9 Summary. 16.10 The Future of Digital Optics. Conclusion. Appendix A: Rigorous Theory of Diffraction. A.1 Maxwell's Equations. A.2 Wave Propagation and the Wave Equation. A.3 Towards a Scalar Field Representation. Appendix B: The Scalar Theory of Diffraction. B.1 Full Scalar Theory. B.2 Scalar Diffraction Models for Digital Optics. B.3 Extended Scalar Models. Appendix C: FFTs and DFTs in Optics. C.1 The Fourier Transform in Optics Today. C.2 Conditions for the Existence of the Fourier Transform. C.3 The Complex Fourier Transform. C.4 The Discrete Fourier Transform. C.5 The Properties of the Fourier Transform and Examples in Optics. C.6 Other Transforms. Index.

Observation of polarization singularities at the nanoscale

Abstract: Diffracted waves are widespread in nature. They can be generated by the scattering with disordered and/or ordered system. Topological defects, such as phase dislocations or polarization singularities, can be hidden in complicated field pattern that arises from this multiple scattering [1]. These singularities are generic properties of waves and can be found in different field of research (tidal theory, optics, Bose-Einstein condensation, superconductivity, superfluidity, high energy physics, etc.).

Unidirectional emission from circular dielectric microresonators with a point scatterer

Abstract: Circular microresonators are micron-sized dielectric disks embedded in material of lower refractive index. They possess modes of extremely high Q-factors (low-lasing thresholds), which makes them ideal candidates for the realization of miniature laser sources. They have, however, the disadvantage of isotropic light emission caused by the rotational symmetry of the system. In order to obtain high directivity of the emission while retaining high Q-factors, we consider a microdisk with a pointlike scatterer placed off-center inside of the disk. We calculate the resulting resonant modes and show that some of them possess both of the desired characteristics. The emission is predominantly in the direction opposite to the scatterer. We show that classical ray optics is a useful guide to optimizing the design parameters of this system. We further find that exceptional points in the resonance spectrum influence how complex resonance wave numbers change if system parameters are varied.

Optical analogue of coherent population trapping via a continuum in optical waveguide arrays

Abstract: A classic wave optics analogue of coherent population trapping of bound states coupled to a common continuum, based on destructive interference of optical tunneling pathways in evanescently-coupled optical waveguides, is theoretically proposed. Our optical model is exactly solvable and allows for a very simple physical explanation of the trapping effect.

Geometric Optics and Boundary Layers for Nonlinear Schrödinger Equations

Abstract: We justify supercritical geometric optics in small time for the defocusing semiclassical Nonlinear Schrodinger Equation for a large class of non-necessarily homogeneous nonlinearities. The case of a half-space with Neumann boundary condition is also studied.

Optical tweezers for undergraduates: Theoretical analysis and experiments

Abstract: A theoretical treatment of optical tweezers is presented at a level suitable for undergraduates. We explore the Rayleigh and the geometrical optics regimes with an emphasis on the latter. We discuss a model for the geometrical optics regime, including spherical aberration effects, and show that the model can easily be implemented numerically. A comparison of the model with experimental data yields excellent agreement between theory and experiment. We also briefly discuss a theory of optical tweezers valid for microspheres of any size.

Useful Analytical Formulae for Near-Field Monostatic Radar Cross Section Under the Physical Optics: Far-Field Criterion

Abstract: Radar cross section (RCS) is usually defined in the far-field zone. In this case, RCS is independent of the range of the radar from the object. However, in several scenarios, like for military applications or measurements led in anechoic chambers, the object is located in the near-field zone. From the physical optics (PO) approximation and from some simplifying assumptions, this paper presents useful analytical formulae of the monostatic RCS of canonical shape perfectly-conducting objects at oblique incidence angles. The formulae are then compared with the PO integral, which requires two-fold numerical integrations. Finally, the authors also examine the far-field criterion using the resulting expressions.

Amplitude and Phase of Tightly Focused Laser Beams in Turbid Media

Abstract: A framework is developed that combines electric field Monte Carlo simulations of random scattering with an angular-spectrum representation of diffraction theory to determine the amplitude and phase characteristics of tightly focused laser beams in turbid media. For planar sample geometries, the scattering-induced coherence loss of wave vectors at larger angles is shown to be the primary mechanism for broadening the focal volume. This approach for evaluating the formation of the focal volume in turbid media is of direct relevance to the imaging properties of nonlinear coherent microscopy, which rely on both the amplitude and phase of the focused fields.

Electromagnetic Scattering Characteristics of PEC Targets in the Terahertz Regime

Abstract: Electromagnetic (EM) scattering characteristics of perfectly electrical conducting (PEC) targets in the terahertz (THz) frequency range are investigated through the use of ray-based high-frequency EM techniques. These techniques include the methods of shooting and bouncing rays (SBR), and the truncated-wedge incremental-length diffraction coefficients (TW-ILDCs). The EM fields associated with each ray are tracked and computed, based on the principle of physical optics (PO) and/or geometrical optics (GO). The total field scattered from the PEC target is then obtained by summing up the EM contributions of each ray and each illuminated edge. In contrast to previously reported applications, these methods are combined together to solve three-dimensional (3D) scattering problems in the THz region. Due to the use of analytical formulas of physical optics and the truncated-wedge incremental-length diffraction coefficients method, the consideration of the multi-reflection effect in shooting and bouncing rays, and partially accounting for the second-order edge-diffraction effects in the truncated-wedge incremental-length diffraction coefficients method, we obtain an extremely efficient algorithm for studying THz scattering. It has excellent agreement with an accurate integral solver, the multilevel fast multipole algorithm (MLFMA), which cannot be used in handling large-scale THz problems. Both mono- and bistatic radar cross sections (RCS) of several PEC objects in the THz band are given to show the correctness and reliability of the asymptotic methods. The EM scattering characteristics of such targets in the THz region are analyzed. Great differences of the target characteristics between the THz and GHz regimes are observed and discussed.

Improved equivalent source theory

Abstract: The equivalent source theorem, which is an important technique in the study of radiation and scattering by apertures, is improved by using the two axioms of the modified theory of physical optics. The method is applied to the problem of radiation of electromagnetic waves by a parallel plate waveguide. The results are investigated numerically.

A Uapo-Based Model for Propagation Prediction in Microcellular Environments

Abstract: A propagation model is presented in this paper for predicting the fleld strength in microcellular environments. According to the Geometrical Theory of Difiraction, the total fleld at a given observation point is calculated by summing the Geometrical Optics contributions and the fleld difiracted by the edges of each structure. The difiraction contributions are here evaluated by means of a Uniform Asymptotic Physical Optics solution to the corresponding canonical problem. Such a solution, expressed in terms of the standard transition function of the Uniform Theory of Difiraction, has resulted to be able to compensate the Geometrical Optics discontinuities at the shadow boundaries. In this framework, the structures are treated as constituted by lossy dielectric materials assumed to be non penetrable. The efiectiveness of the here proposed model has been tested in some typical scenarios by means of comparisons with the Finite Difierence Time Domain method.

Extreme Ultraviolet Lithography

Abstract: Master Extreme Ultraviolet Lithography Techniques Produce high-density, ultrafast microchips using the latest EUVL methods. Written by industry experts, Extreme Ultraviolet Lithography details the equipment, materials, and procedures required to radically extend fabrication capabilities to wavelengths of 32 nanometers and below. Work with masks and resists, configure high-reflectivity mirrors, overcome power and thermal challenges, enhance resolution, and minimize wasted energy. You will also learn how to use Mo/Si deposition technology, fine-tune performance, and optimize cost of ownership. Design EUVL-ready photomasks, resist layers, and source-collector modules Assemble optical components, mirrors, microsteppers, and scanners Harness laser-produced and discharge pulse plasma sources Enhance resolution using proximity correction and phase-shift Generate modified illumination using holographic elements Measure critical dimensions using metrology and scatterometry Deploy stable Mo/Si coatings and high-sensitivity multilayers Handle mask defects, layer imperfections, and thermal instabilities Table of contents Preface Chapter 1. Wigner Distribution in Optics Chapter 2. Ambiguity Function in Optical Engineering Chapter 3. Rotations in Phase Space Chapter 4. The Radon-Wigner Transform in Analysis, Design, and Processing of Optical Signals Chapter 5. Imaging Systems: Phase-Space Representations Chapter 6. Super Resolved Imaging in Wigner-Based Phase Space Chapter 7. Radiometry, Wave Optics, and Spatial Coherence Chapter 8. Rays and Waves Chapter 9. Self-Imaging in Phase Space Chapter 10. Sampling and Phase Space Chapter 11. Phase Space in Ultrafast Optics Index

Near-field beam pattern measurement of qualification model of ALMA band 8 (385–500 GHz) cartridge receiver

Abstract: We have developed a near-field vector beam measurement system covering the range of frequencies from 385 to 500 GHz. The measurement set-up is capable of measurements with dynamic range exceeding 50 dB and amplitude and phase stability respectively of 0.1 dB/h and 1 degree/5 min at room temperature. Beam patterns of the ALMA band 8 corrugated horns and receiver optics block were measured at room temperature and lately compared with physical optics calculations obtained in the far-field. Both co-polar and cross-polar beam patterns of a qualification model of the ALMA band 8 cartridge cooled in a cartridge-test-cryostat have also been measured in the near-field as a detector of a submillimeter vector network analyzer. The measurements presented in this work refer to the lowest, middle and upper frequencies of band 8. The comparisons between software model and experimental measurements at these frequencies show good agreement down to −30 dB for the main polarization component. The cross-polarization level of the beam propagating through the receiver optics block was also characterized. We found that a cross-polarization level better than −28 dB can be achieved at all measured frequencies. The measured beam pattern of this receiver corresponds to efficiency of greater than 92% at the sub reflector (diameter of 750 mm) of the ALMA 12 m optics.

Characterization of dense focal plane array feeds for parabolic reflectors in achieving closely overlapping or widely separated multiple beams

Abstract: [1] In the advent of modern mobile satellite communications requiring rapid and adaptive multiple beams, this work studies the ability of reflector antennas fed by dense focal plane arrays (FPA) in achieving arbitrarily shaped and sized footprints to meet the demands In this paper, the efficiencies of single off-axis as well as multiple beams of FPA-fed paraboloids are investigated The offset FPA considered here comprises hard rectangular waveguides The focal plane field, which the FPA samples, is synthesized by integration of the physical optics induced electric currents over the reflector surface caused by the off-axis incident plane wave arriving at that incidence angle of interest Full mutual coupling analysis has been performed in the FPA sampling, thereby taking into account mutual coupling losses in the arrays The fields over the tilted elliptical aperture of off-axis beams needed for calculation of the aperture efficiency are obtained by projecting the usual focal plane fields to this tilted aperture using geometrical optics Results show that the total efficiency of the offset FPA-fed reflector decreases with increasing beam angle and increases with larger number of FPA elements It is also found that the maximum directive gain of the reflector radiation patterns falls noticeably with beam angle when the FPA population is low, but the directivity can be maintained well when an adequate number of FPA elements are used Multiple beams that are either closely overlapping or widely separated are also successfully investigated

Composite Electromagnetic Scattering from the Plate Target Above a One-Dimensional Sea Surface: Taking the Diffraction into Account

Abstract: The properties of composite electromagnetic scattering from a square conducting plate target above a one-dimensional sea surface are discussed with the diffraction of plate edge taken into account. The characteristics of electromagnetic scattering from the sea surface are investigated based on the Kirchhoff Approximation (KA). The backscattering field of a plate target is calculated with the method of higher equivalent edge currents. Besides, the method of equivalent edge currents (MEC), Physical Optics (PO) approximation and the reciprocity theorem method are combined to calculate the composite scattering field from the conducting plate target above a sea surface. The effect of the plate size, inclination, edge diffraction and the frequency of incident wave on the composite scattering field is analyzed.

A Uapo-Based Solution for the Scattering by a Lossless Double-Negative Metamaterial Slab

Abstract: A closed form solution is here proposed for evaluating the fleld difiracted by the edge of a lossless, isotropic and homogeneous double-negative metamaterial slab when illuminated by a plane wave at skew incidence. It is obtained by considering a Physical Optics approximation of the electric and magnetic equivalent surface currents in the radiation integral and by performing a uniform asymptotic evaluation of this last. The flnal expression is given in terms of the Geometrical Optics response of the structure and the standard transition function of the Uniform Geometrical Theory of Difiraction, so that it results easy to handle and simple to implement in a computer code. As demonstrated by numerical tests, it allows one to compensate the discontinuities of the Geometrical Optics fleld at the re∞ection and incidence shadow boundaries. Moreover, the accuracy of the solution is well assessed by means of comparisons with a commercial tool based on Finite Element Method.