Geometrical Optics

Flatland'' is the title of a 120-year-old science fiction story. It describes the life of creatures living in a twodimensional (2D) Flatland. A superior creature living in the three-dimensional (3D) spaceland, as we do, can easily inspect, for example, the inside of a Flatland house, as well as the content of a flat man's stomach without leaving any trace. Furthermore, the 3D person has supernatural powers that enable him to change the laws of physics in Flatland. We present here the concept of a 2D Flatland optics with one transversal coordinate x and one longitudinal coordinate z. The other transversal coordinate y allows total inspection of Flatland optics, and the freedom to change the wavelength, without using something like nonlinear optics or a Doppler shift. Monochromatic 3D light can be converted reversibly into polychromatic 2D light. A large variety of 2D systems and 2D effects will be presented here and in follow-up contributions. An epilogue faces the question, how ''real'' is Flatland optics? © 2000 Optical Society of America [S0740-3232(00) 00710-9]

In ''Flatland optics: fundamentals'' [J. Opt. Soc. Am. A 17, 1755 (2000)] we described the basic principles of two-dimensional (2D) optics and showed that a wavelength in three-dimensional (3D) space (x,y,z) may appear in Flatland (x,z) as a wave with another wavelength, ⌳ ϭ /cos␣. The tilt angle ␣ can be modified by a 3D (Spaceland) individual who then is able to influence the 2D optics in a way that must appear to be magical to 2D Flatland individuals-in the spirit of E. A. Abbott's science fiction story [Flatland, a Romance of Many Dimensions, 6th ed. (Dover, New York, 1952)] of 1884. We now want to establish the reality or objectivity of the 2D wavelength ⌳ by some basic experiments similar to those that demonstrated roughly 200 years ago the wave nature of light. Specifically, we describe how to measure the 2D wavelength ⌳ by mean of five different arrangements that involve Young's biprism configuration, Talbot's self-imaging effect, measuring the focal length of a Fresnel zone plate, and letting light be diffracted by a double slit and by a grating. We also performed experiments with most of these arrangements. The results reveal that the theoretical wavelength, as predicted by our Flatland optics theory, does indeed coincide with the wavelength ⌳ as measured by Flatland experiments. Finally, we present an alternative way to understand Flatland optics in the spatial frequency domains of Flatland and Spaceland.

The Point-Spread-Function (PSF) field characterizes the geometric and diffractive properties of most optical system designs for imaging applications. The conventional method of computing the PSF field is carried out in two steps: first, geometrical computation of the wave aberration function, and then, diffraction evaluation. That method usually applies two approximations: 1) the exit and entrance pupil ray intersection coordinates are equal; and 2) the optical field amplitude distribution does not change between exit and entrance pupil planes. We propose here a variation of the conventional method that allows overcoming these two approximations in axially symmetric optical systems. To show the potentials of the method we applied it to a Cooke triplet. We analyze the influence of the number of traced rays on the measured accuracy of the method. We also evaluate the differences in the PSF estimation accuracy with respect to a method where the two aforementioned approximations were used.

Research has shown that students have tremendous difficulties developing a qualitative understanding of wave optics, at all educational levels. In this study, we investigate how three different approaches to visualizing light waves affect students' understanding of wave optics. In the first, the conventional, approach light waves are represented by sinusoidal curves. The second teaching approach includes representing light waves by a series of static images, showing the oscillating electric field vectors at characteristic, subsequent instants of time. Within the third approach phasors are used for visualizing light waves. A total of N ¼ 85 secondary school students were randomly assigned to one of the three teaching approaches, each of which lasted a period of four class hours. Students who learned with phasors and students who learned from the series of static images outperformed the students learning according to the conventional approach, i.e., they showed a much better understanding of basic wave optics, as measured by a conceptual survey administered to the students one week after the treatment. Our results suggest that visualizing light waves with phasors or oscillating electric field vectors is a promising approach to developing a deeper understanding of wave optics for students enrolled in conceptual level physics courses.

The celestial illusions, in particular the moon and sun illusion, are among the enduring problems of visual size and depth perception, the attempts to solve which go back to the antiquity. It is perhaps the longest-standing aporia in the history of the theory of perception, which has been tried in vain in various ancient cultures – in Egypt, China and Greece – and continued to be tackled in the Middle Ages and modern times by many renowned philosophers, mathematicians and scientists of optics. The following essay is an attempt to outline the historicity of this hitherto unresolved problem and to re-examine its topicality. The insolubility and historically incessant persistence of this aporia in visual space perception can be traced back, on the one hand, to the dichotomisation between the intromission and extramission theories of vision that was already undertaken in ancient times and, on the other hand, to the almost philosophically and paradigmatically established internalism in the theory of perception in the Cartesian-Kantian modernity. The study elucidates the topicality of the flattened dome theory as proposed by Alhazen (Ibn al-Haytham) in the 11th century, which, how I would argue, presupposes a unique externalism in visual perception, or the objective externalisation of the process of vision, rather than an internalism that has been tacitly assumed from the antiquity and Middle Ages to the present day.

We investigate a new afocal two freeform mirror design problem in first order optics. The resulting first-order partial differential equations for the freeform two mirror system have an analytic solution with the sole condition that the x-y and x'-y' axes are parallel. Two selected solutions are presented. One of them is semiaplanatic (fulfilling the aplanatic condition only for the x-coordinates), while the other is, to our knowledge, the first example of an aplanatic two-mirror system without rotational symmetry. OCIS codes: (080.2720) Mathematical methods (general); (080.2740) Geometric optical design; (080.3620) Lens system design; (080.4225) Nonspherical lens design; (080.4298) Nonimaging optics.

The energy efficiency and compactness of an illumination system are two main concerns in illumination design for extended sources. In this paper, we present two methods to design compact, ultra efficient aspherical lenses for extended Lambertian sources in two-dimensional geometry. The light rays are directed by using two aspherical surfaces in the first method and one aspherical surface along with an optimized parabola in the second method. The principles and procedures of each design method are introduced in detail. Three examples are presented to demonstrate the effectiveness of these two methods in terms of performance and capacity in designing compact, ultra efficient aspherical lenses. The comparisons made between the two proposed methods indicate that the second method is much simpler and easier to be implemented, and has an excellent extensibility to three-dimensional designs.

From the literature the analytical calculation of local power and astigmatism of a wavefront after refraction and propagation is well known; it is, e.g., performed by the Coddington equation for refraction and the classical vertex correction formula for propagation. Recently the authors succeeded in extending the Coddington equation to higher order aberrations (HOA). However, equivalent analytical propagation equations for HOA do not exist. Since HOA play an increasingly important role in many fields of optics, e.g., ophthalmic optics, it is the purpose of this study to extend the propagation equations of power and astigmatism to the case of HOA (e.g., coma and spherical aberration). This is achieved by local power series expansions. In summary, with the results presented here, it is now possible to calculate analytically the aberrations of a propagated wavefront directly from the aberrations of the original wavefront containing both low-order and high-order aberrations.

Starting from a Hamiltonian description of the photon within the set of Bargmann-Wigner equations we derive new semiclassical equations of motion for the photon propagating in static gravitational field. These equations which are obtained in the representation diagonalizing the Hamiltonian at the order h, present the first order corrections to the geometrical optics. The photon Hamiltonian shows a new kind of helicity-torsion coupling. However, even for a torsionless space-time, photons do not follow the usual null geodesic as a consequence of an anomalous velocity term. This term is responsible for the gravitational birefringence phenomenon: photons with distinct helicity follow different geodesics in a static gravitational field.

In this article we describe the generation of the evanescent waves which are present in the rarer medium at total reflection by using a mixed-type system, the Ludwig system, which leads naturally to consider a complex-valued phase. The Ludwig system is derived from the Helmholtz equation by using an appropriate modification of the stationary phase procedure: the Chester, Friedman and Ursell's method. The passage from the illuminated to the shadow region is described by means of the ray switching mechanism based on the Stokes phenomenon applied to the Airy function. Finally, the transport system connected to the Ludwig eikonal system is studied in the case of linear wavefronts and the existence of the Goos-Hänchen effect is proved.

The analysis of wave motion in infinite homogeneous waveguides, having a complicated cross-section and/or an irregular inclusion, is a rather difficult task for the majority of available methods, especially when striving for accurate results. In contrast, this presented procedure performed in the frequency domain, is simple to apply. It yields correct results because the radiation conditions are considerably accurately satisfied, and it offers a clear parametric insight into wave motion. This procedure uses the FE modelling of an analysed section of the waveguide. It is based on the decomposition of wave motion, distinguishing propagating and non-propagating wavemodes by solving the eigenvalue problem. The presented examples demonstrate the effectiveness of this procedure, whilst a comparison between computed and analytical results demonstrates its accuracy.

An active bistatic LIDAR system operating through atmospheric turbulence is considered. Illumination field is assumed to be an electromagnetic Gaussian-Schell model beam. Target surface is modeled as a combination of isotropic phase screen governed by Gaussian statistics, to account for its roughness, and a Gaussian lens to account for its size and radius of curvature. With the help of a recently developed tensor method for propagation of stochastic electromagnetic beams through ABCD systems and random media we examine the evolution of states of coherence and polarization of the beam. In the case of unresolved flat (planar) target we show that by comparing coherence and polarization properties of the illumination beam and of the return beam it is possible to predict the typical roughness of the target surface.

In this article, we present a fully analytical model for the evaluation of the electromagnetic (EM) field scattered from a composite target in a generic bistatic configuration. The scenario comprises a rectangular parallelepiped target with smooth dielectric faces lying over a rough background surface, modeled as a stochastic process. The single-and multiplebounce scattering contributions arising from the target, the rough background, and their interactions have been derived under the Kirchhoff approximation (KA)-geometrical optics (GO) solution. This framework enables the evaluation of the bistatic radar cross section (RCS) of the considered composite target via closedform expressions. The proposed model exhibits good agreement with the literature results based on accurate and well-established numerical methods. Our analytical model is therefore proposed as a valid alternative to numerical techniques, being able to provide reliable results at a negligible computational burden. Finally, the role of the main scene parameters, i.e., target orientation, surface roughness, and polarization in the bistatic RCS of the target, have been analyzed and discussed.

This paper furnishes a convenient theoretical framework for the analytical evaluation of the bistatic scattering coefficients, under the Kirchhoff approximation (KA) in electromagnetics. Starting from the KA, specific results under the geometrical optics and physical optics approximations are furnished, along with the backscattering geometry. The main aim is to provide closed‐form expressions of the scattering matrix that are suited to scenarios where multiple‐bounce scattering comes into play and/or surfaces with arbitrary unit normal are present. This is accomplished by addressing the following objectives: (1) to provide an explicit formulation of the scattering matrix under KA in terms of the incident and scattered unit wave vectors, (2) to provide a more generic derivation of the scattering matrix under the physical optics approximation by relaxing typical hypotheses regarding the geometry of the scattering problem, and (3) to highlight some important symmetries of the scatterin...

This paper deals with the mirror rotation problem and the problem of rotation of refracting surface in ray optics. These two problems of rotation in ray optics have been dealt with on the basis of the generalized vectorial laws of reflection and refraction discovered by the author in 2005. In addition to the development of many interesting physical insights to the aforesaid rotation problems in ray optics, the most remarkable fact that has been discovered in the present study is that the proposition 'Velocity of light is unattainable' is not correct. Rather, it is possible to have velocity exceeding the velocity of light -a result not in agreement with the special theory of relativity.

We study classification problems for generic isotropic submanifolds. The classification list of simple and unimodal singularities is obtained and the generic evolutions of quasicaustics in small dimension are classified. Examples encountered in geometric optics are presented.

This work is based on studying, implementing and analyzing the phenomenon of electromagnetic scattering caused by canonical surfaces. The study is made possible by Geometric Optics (GO Geometrical Optics) and Uniform Theory of Diffraction (UTD), asymptotic techniques that use a combination of ray tracing to obtain the result of the electromagnetic field spread. The results are obtained by tracking trajectories generated between transmitter and receiver, determined by algorithms that trace the reflected and diffracted rays in a two dimensional space based on the images method. The calculation is done in the frequency domain and deterministically, generating results of the individual contributions of each radius in the final result of the observed field. The phenomenon was analyzed in a perfect electrical conducting wedge (without losses) and only in incident fields with flat wave fronts (single angle of incidence), because the analytical solution only admits fields with this characte...

Geometrical optics limit of the Maxwell equations for nonlinear media with the Cole–Cole dependence of dielectric function and magnetic permeability on the frequency is considered. It is shown that for media with slow variation along one axis such a limit gives rise to the dispersionless Veselov–Novikov equation for the refractive index. It is demonstrated that the Veselov–Novikov hierarchy is amenable to the quasiclassical ‐dressing method. Under more specific requirements for the media, one gets the dispersionless Kadomtsev–Petviashvili equation. Geometrical optics interpretation of some solutions of the above equations is discussed.

It is shown that the geometrical optics limit of the Maxwell equations for certain nonlinear media with slow variation along one axis and particular dependence of dielectric constant on the frequency and fields gives rise to the dispersionless Veselov-Novikov equation for refractive index. It is demonstrated that the last one is amenable to the quasiclassical∂-dressing method. A connection is noted between geometrical optics phenomena under consideration and quasiconformal mappings on the plane.

We present a new version of our optical model for solar cell simulation: GENPRO4. Its working principles are briefly explained. The model is suitable for quickly and accurately simulating a wide range of wafer based and thin-film solar cells. Especially adjusting layer thicknesses to match the currents in multi-junction devices can be done with a minimum of computational cost. To illustrate this, a triple junction thin-film silicon solar cell is simulated. The simulation results show very good agreement with EQE measurements. The application of an MgF 2 anti-reflective coating or an anti-reflective foil with pyramid texture is considered. Their effects on the implied photocurrents of top, middle and bottom cell are investigated in detail.

The aim of the present work is to obtain an integral representation of the field associated with the refraction of a plane wave by an arbitrary surface. To this end, in the first part we consider two optical media with refraction indexes n 1 and n 2 separated by an arbitrary interface, and we show that the optical path length, Φ, associated with the evolution of the plane wave is a complete integral of the eikonal equation in the optical medium with refraction index n 2. Then by using the k function procedure introduced by Stavroudis, we define a new complete integral, S, of the eikonal equation. We remark that both complete integrals in general do not provide the same information; however, they give the geometrical wavefronts, light rays, and the caustic associated with the refraction of the plane wave. In the second part, using the Fresnel-Kirchhoff diffraction formula and the complete integral, S, we obtain an integral representation for the field associated only with the refraction phenomena, the geometric field approximation, in terms of secondary plane waves and the k-function introduced by Stavroudis in solving the problem from the geometrical optics point of view. We use the general results to compute: the wavefronts, light rays, caustic, and the intensity associated with the refraction of a plane wave by an axicon and plano-spherical lenses.

Scattered light patterns produced by spherical transparent particles of a wide range of diameters (1-100 /im) and for a useful range of forward scattering angles (0-200) are calculated by using both Lorenz-Mie theory and geometrical optics theory. A detailed comparison of the results leads to a definitive assessment of the accuracy of geometrical optics theory in the forward direction. Emphasis is put on simultaneous sizing and velocimetry of particles using pedestal calibration methods. for which Lorenz-Mie theory predictions usually exist, or they have utilized simplified geometrical optics to compute the scattering from larger particles. These geometrical optics computations have generally either utilized Fraunhofer diffraction only, or they have used white light waves, which simplifies the inclusion of reflection and refraction of light. Geometrical optics calculations are carried out by assuming that A.

Constructing ray diagrams to locate the image of an object formed by thin lenses and mirrors is a staple of many introductory physics courses at the high school and college levels, and has been the subject of some pedagogy-related articles. Our review of textbooks distributed in the United States suggests that the singular approach involves drawing principle rays to locate an object's image. We were pleasantly surprised to read an article in this journal by Suppapittayaporn et al. in which they use an alternative method to construct rays for thin lenses based on a “tilted principle axis” (TPA). In particular, we were struck by the generality of the approach (a single rule for tracing rays as compared to the typical two or three rules), and how it could help students more easily tackle challenging situations, such as multi-lens systems and occluded lenses, where image construction using principle rays may be impractical. In this paper, we provide simple “proofs” for this alternat...

We investigate a new afocal two freeform mirror design problem in first order optics. The resulting first-order partial differential equations for the freeform two mirror system have an analytic solution with the sole condition that the x-y and x'-y' axes are parallel. Two selected solutions are presented. One of them is semiaplanatic (fulfilling the aplanatic condition only for the x-coordinates), while the other is, to our knowledge, the first example of an aplanatic two-mirror system without rotational symmetry. OCIS codes: (080.2720) Mathematical methods (general); (080.2740) Geometric optical design; (080.3620) Lens system design; (080.4225) Nonspherical lens design; (080.4298) Nonimaging optics.

The energy efficiency and compactness of an illumination system are two main concerns in illumination design for extended sources. In this paper, we present two methods to design compact, ultra efficient aspherical lenses for extended Lambertian sources in two-dimensional geometry. The light rays are directed by using two aspherical surfaces in the first method and one aspherical surface along with an optimized parabola in the second method. The principles and procedures of each design method are introduced in detail. Three examples are presented to demonstrate the effectiveness of these two methods in terms of performance and capacity in designing compact, ultra efficient aspherical lenses. The comparisons made between the two proposed methods indicate that the second method is much simpler and easier to be implemented, and has an excellent extensibility to three-dimensional designs.

We study the problem of the behaviour of a quantum massless scalar field in the space between two parallel infinite perfectly conducting plates, one of them stationary, the other moving periodically. We reformulate the physical problem into a problem about the asymptotic behaviour of the iterates of a map of the circle, and then apply results from the theory of dynamical systems to study the properties of the map. Many of the general mathematical properties of maps of the circle translate into properties of the field in the cavity. For example, we give a complete classification of the possible resonances in the system, and show that small enough perturbations do not destroy the resonances. We use some mathematical identities to give a transparent physical interpretation of the processes of creation and amplification of the quantum field due to the motion of the boundary and to elucidate the similarities of and the differences between the classical and quantum fields in domains with moving boundaries.

A comparison of theories describing two laser photothermal lens signals is given. The aberrant nature of this lens is accounted for in a theory which treats the propagation of a monitor laser in terms of a phase shift in this laser beam wave front. The difference between theories are discussed in terms of the predicted signal strengths and temporal behavior. The aberrant theory results in smaller theoretical signal strengths and different functional relationships between signal and analyte level.

This paper presents a new model for prediction of wave propagation in indoor and outdoor environments. The method is based on twodimensional ray-tracing techniques using image theory to determine all valid paths. The computation of fields is based on geometrical optics and uniform theory of diffraction. A new approach for transmitted rays through the walls is proposed and validated by comparison with results obtained via the finite-difference time-domain method. Results for a practical indoor environment are presented by mapping the received power.

Este artículo tiene como objetivo emplear conceptos de geometría plana para deducir el ángulo formado en un plano inclinado. Esta deducción es fundamental para resolver una amplia gama de problemas en física estática y dinámica. Una dificultad común entre los estudiantes es la representación correcta de este ángulo en un diagrama de cuerpo libre, independientemente de la orientación del plano inclinado.

This study aims at describing the field propagation in terms of pulsed rays, that are particularly advantageous when dealing with short-pulse excitations. In the framework of the Geometrical Theory of Diffraction we augment Geometrical Optics and uniform singly diffracted field solutions available in the time domain (TD), by TD doubly diffracted (DD) rays, that are expressed in simple closed forms. Impulsive double diffraction at a pair of coplanar edges is here formulated directly in the TD, as a double superposition of impulsive spherical waves. Nonuniform and uniform wavefront approximations for TD-DD fields are determined in closed form, defining two novel TD transition functions. The scalar case with either hard or soft boundary conditions is analyzed first, and then used to build an electromagnetic dyadic DD coefficient for a pair of coplanar edges with perfectly conducting faces. Particular attention is given to the definition of TD transition regions, i.e., the elliptical regions where the TD-DD field does not exhibit a ray optical behavior. The compensation mechanism by which the TD-DD fields repair the discontinuity introduced by singly diffracted fields at their shadow boundaries is also analyzed in detail. Our result for the TD-DD field excited by an impulsive spherical wave is valid only for early times, at and close to (behind) the DD ray wavefront. The TD-DD field response to a more general pulsed excitation is obtained via convolution, and if the exciting signal has no low-frequency components the range of validity of the resulting pulsed response is enlarged to later observation times behind the wavefront. Index Terms-Diffraction, electromagnetic transient analysis, ray tracing, time domain (TD) analysis, transient propagation, transient scattering, wedges. Filippo Capolino (S'94-M'97-SM'04) was born in Florence, Italy, in 1967. He received the Laurea degree (cum laude) in electronic engineering and the Ph.D. degree from the

In this study, the edge diffraction of a TM-polarized electromagnetic plane wave by two-dimensional dielectric wedges has been analyzed. An asymptotic solution for the radiation field has been derived from equivalent electric and magnetic currents which can be determined by the geometrical optics (GO) rays. This method may be regarded as an extended version of physical optics (PO). The diffracted field has been represented in terms of cotangent functions whose singularity behaviors are closely related to GO shadow boundaries. Numerical calculations are performed to compare the results with those by other reference solutions, such as the hidden rays of diffraction (HRD) and a numerical finite-difference time-domain (FDTD) simulation. Comparisons of the diffraction effect among these results have been made to propose additional lateral waves in the denser media.

In the first paper of this series the author described a closed-form analytical approach to obtaining the complete solution set for four-mirror anastigmats in which all the mirrors were spherical. Two novel types of four-spherical-mirror anastigmat with concave primary were reported. This approach has been modified by setting up baseline systems with good first-order characteristics and adding the minimum number of aspheres necessary to provide anastigmatic correction. In this way, searches for useful four-mirror anastigmats with one, two or three-mirrors kept strictly spherical have been carried out. The example given in this paper shows that by using this technique a system with only one conicoid mirror can be found which has very similar first-order properties and equivalent correction to a system with three conicoids.

We used Geometric Algebra to compute the paths of skew rays in a cylindrical, step-index multimode optical fiber. To do this, we used the vector addition form for the law of propagation, the exponential of an imaginary vector form for the law of refraction, and the juxtaposed vector product form for the law of reflection. In particular, the exponential forms of the vector rotations enables us to take advantage of the addition or subtraction of exponential arguments of two rotated vectors in the derivation of the ray tracing invariants in cylindrical and spherical coordinates. We showed that the light rays inside the optical fiber trace a polygonal helical path characterized by three invariants that relate successive reflections inside the fiber: the ray path distance, the difference in axial distances, and the difference in the azimuthal angles. We also rederived the known generalized formula for the numerical aperture for skew rays, which simplifies to the standard form for meridional rays.

We derive the paraxial meridional ray tracing equations from the unified reflection-refraction law using geometric algebra. This unified law states that the normal vector to the interface is a rotation of the incident ray or of the refracted ray or of the reflected ray by an angle equal to the angle of incidence or of refraction. We obtain the finite meridional ray tracing equations by simply equating the arguments of the exponential rotation operators. We then derive the paraxial limits of these equations with the help of sign function identities. We show that by embedding the sign functions in the ray tracing equations, we explicitly declare our chosen sign conventions in symbols and not in prose.

Mikrogerit anten yapilannm; hafiflik, ucuzluk, yiizeysel kolay kullanim ve diger devrelerle tiimlegtirilebilme gibi 6nemli Bzellikleri nedeniyle, iizerinde genig olpiide paligmalar y a p h i $ ve pok &tli kullanim alanlan bulunmqtur.Ku bandinda iki farkli uydudan gelen yayinlan iziemek ipin, kupixk ve hllamgli bir alici anten sistemi tasanm paligmasi yapilmighr. Sistem belirli bir boylam farhnda yerlegtirilmig iki farkh uyduda bulunan igmtleri, elekhonik olarak ,gin demetini kaydrarak alia sisteme ilgili TVmata ipretleri aktarabilecek Bzellikte olacakhr. Ayni zamanda hareketli all? noktalannda da ban eklemelerle, uydu igaret aliqi gevklegtirebilecek lizellige sahip olabilecektir. Bu pahgmada iki ayn ism demetine sahip uydu alia anteni ipin hem elektromagnetik hem de elektronik devre gevklegtirimindeki zorluklar ve uygulamada kaqilqilan sorunlara iligkin p a z m yirntemleri geligtirilmi$ir.

It is shown that, within the limits of geometrical optics, it is possible to specify a pure-phase pupil function that will produce any desired optical transfer function (OTF) or point spread function (PSF) in an incoherent optical processing system. A general prescription for finding the pupil function is presented, and specific analytical results are given for simple power-law PSFs. As an example, the fabrication and testing of a logarithmic phase plate that produces an appropriate PSF for incoherent optical processing of transaxial tomography data are discussed.

A promising route to smaller, powerful cameras built into smartphones and other devices is to design optical elements that manipulate light by diffraction-the bending of light around obstacles or through small gapsinstead of refraction. [15] Converting a single photon from one color, or frequency, to another is an essential tool in quantum communication, which harnesses the subtle correlations between the subatomic properties of photons (particles of light) to securely store and transmit information. Scientists at the National Institute of Standards and Technology (NIST) have now developed a miniaturized version of a frequency converter, using technology similar to that used to make computer chips. [14] Harnessing the power of the sun and creating light-harvesting or light-sensing devices requires a material that both absorbs light efficiently and converts the energy to highly mobile electrical current. Finding the ideal mix of properties in a single material is a challenge, so scientists have been experimenting with ways to combine different materials to create "hybrids" with enhanced features. [13] Condensed-matter physicists often turn to particle-like entities called quasiparticles-such as excitons, plasmons, magnons-to explain complex phenomena. Now Gil Refael from the California Institute of Technology in Pasadena and colleagues report the theoretical concept of the topological polarition, or "topolariton": a hybrid half-light, half-matter quasiparticle that has special topological properties and might be used in devices to transport light in one direction. [12] Solitons are localized wave disturbances that propagate without changing shape, a result of a nonlinear interaction that compensates for wave packet dispersion. Individual solitons may collide, but a defining feature is that they pass through one another and emerge from the collision unaltered in shape, amplitude, or velocity, but with a new trajectory reflecting a discontinuous jump. Working with colleagues at the Harvard-MIT Center for Ultracold Atoms, a group led by Harvard Professor of Physics Mikhail Lukin and MIT Professor of Physics Vladan Vuletic have managed to coax photons into binding together to form molecules-a state of matter that, until recently, had been purely theoretical. The work is described in a September 25 paper in Nature. New ideas for interactions and particles: This paper examines the possibility to origin the Spontaneously Broken Symmetries from the Planck Distribution Law. This way we get a Unification of the Strong, Electromagnetic, and Weak Interactions from the interference occurrences of oscillators. Understanding that the relativistic mass change is the result of the magnetic induction we arrive to the conclusion that the Gravitational Force is also based on the electromagnetic forces, getting a Unified Relativistic Quantum Theory of all 4 Interactions. Driven to diffraction New nanodevice shifts light's color at single-photon level Quantum dots enhance light-to-current conversion in layered semiconductors Quasiparticles dubbed topological polaritons make their debut in the theoretical world 'Matter waves' move through one another but never share space Photonic molecules The Electromagnetic Interaction