Results for "Steven G. Johnson"
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Numerical methods for computing Casimir interactionsJul 03 2010Oct 01 2010We review several different approaches for computing Casimir forces and related fluctuation-induced interactions between bodies of arbitrary shapes and materials. The relationships between this problem and well known computational techniques from classical ... More Saddle-point integration of $C_\infty$ "bump" functionsAug 18 2015This technical note describes the application of saddle-point integration to the asymptotic Fourier analysis of the well-known $C_\infty$ "bump" function $\exp[-(1-x^2)^{-1}]$, deriving both the asymptotic decay rate $k^{-3/4} \exp(-\sqrt k)$ of the Fourier ... More Electromagnetic Wave Source ConditionsJan 23 2013This chapter discusses the relationships between current sources and the resulting electromagnetic waves in FDTD simulations. First, the "total-field/scattered-field" approach to creating incident plane waves is reviewed and seen to be a special case ... More Optical "Bernoulli" forcesMay 02 2013Sep 12 2013By Bernoulli's law, an increase in the relative speed of a fluid around a body is accompanies by a decrease in the pressure. Therefore, a rotating body in a fluid stream experiences a force perpendicular to the motion of the fluid because of the unequal ... More Scalable computation of Jordan chainsApr 19 2017Apr 24 2017We present an algorithm to compute the Jordan chain of a nearly defective matrix with a $2\times2$ Jordan block. The algorithm is based on an inverse-iteration procedure and only needs information about the invariant subspace corresponding to the Jordan ... More Speed-of-light limitations in passive linear mediaMay 01 2014We prove that well-known speed of light restrictions on electromagnetic energy velocity can be extended to a new level of generality, encompassing even nonlocal chiral media in periodic geometries, while at the same time weakening the underlying assumptions ... More Topology optimization of freeform large-area metasurfacesFeb 08 2019We demonstrate optimization of optical metasurfaces over $10^5$--$10^6$ degrees of freedom in two and three dimensions, 100--1000+ wavelengths ($\lambda$) in diameter, with 100+ parameters per $\lambda^2$. In particular, we show how topology optimization, ... More Radiative heat transfer in nonlinear Kerr mediaJun 16 2014Feb 24 2015We obtain a fluctuation--dissipation theorem describing thermal electromagnetic fluctuation effects in nonlinear media that we exploit in conjunction with a stochastic Langevin framework to study thermal radiation from Kerr ($\chi^{(3)}$) photonic cavities ... More Transformation Inverse DesignApr 04 2013May 22 2013We present a new technique for the design of transformation-optics devices based on large-scale optimization to achieve the optimal effective isotropic dielectric materials within prescribed index bounds, which is computationally cheap because transformation ... More Shape-Independent Limits to Near-Field Radiative Heat TransferApr 06 2015Oct 14 2015We derive shape-independent limits to the spectral radiative heat-transfer rate between two closely spaced bodies, generalizing the concept of a black body to the case of near-field energy transfer. Through conservation of energy and reciprocity, we show ... More Degenerate four-wave mixing in triply-resonant Kerr cavitiesNov 26 2010We demonstrate theoretical conditions for highly-efficient degenerate four-wave mixing in triply-resonant nonlinear (Kerr) cavities. We employ a general and accurate temporal coupled-mode analysis in which the interaction of light in arbitrary microcavities ... More Casimir repulsion beyond the dipole regimeMay 02 2011We extend a previous result [Phys. Rev. Lett. 105, 090403 (2010)] on Casimir repulsion between a plate with a hole and a cylinder centered above it to geometries in which the central object can no longer be treated as a point dipole. We show through numerical ... More Achieving a Strongly Temperature-Dependent Casimir EffectApr 15 2010We propose a method of achieving large temperature sensitivity in the Casimir force that involves measuring the stable separation between dielectric objects immersed in fluid. We study the Casimir force between slabs and spheres using realistic material ... More Floquet Chern Insulators of LightFeb 22 2019Achieving topologically-protected robust transport in optical systems has recently been of great interest. Most topological photonic structures can be understood by solving the eigenvalue problem of Maxwell's equations for a static linear system. Here, ... More Inverse design of large-area metasurfacesAug 13 2018Dec 14 2018We present a computational framework for efficient optimization-based "inverse design" of large-area "metasurfaces" (subwavelength-patterned surfaces) for applications such as multi-wavelength and multi-angle optimizations, and demultiplexers. To optimize ... More Casimir forces in the time domain: I. TheoryApr 01 2009Apr 21 2009We introduce a method to compute Casimir forces in arbitrary geometries and for arbitrary materials based on the finite-difference time-domain (FDTD) scheme. The method involves the time-evolution of electric and magnetic fields in response to a set of ... More Secondary ionization and heating by fast electronsOct 23 2009We examine the fate of fast electrons (with energies E>10 eV) in a thermal gas of primordial composition. To follow their interactions with the background gas, we construct a Monte Carlo model that includes: (1) electron-electron scattering (which transforms ... More Floquet Chern Insulators of LightFeb 22 2019Mar 14 2019Achieving topologically-protected robust transport in optical systems has recently been of great interest. Most topological photonic structures can be understood by solving the eigenvalue problem of Maxwell's equations for a static linear system. Here, ... More All-optical three-dimensional electron pulse compressionSep 23 2014Jan 28 2015We propose an all-optical, three-dimensional electron pulse compression scheme in which Hermite-Gaussian optical modes are used to fashion a three-dimensional optical trap in the electron pulse's rest frame. We show that the correct choices of optical ... More Casimir repulsion between metallic objects in vacuumMar 17 2010Aug 06 2010We give an example of a geometry in which two metallic objects in vacuum experience a repulsive Casimir force. The geometry consists of an elongated metal particle centered above a metal plate with a hole. We prove that this geometry has a repulsive regime ... More Casimir forces in the time domain II: ApplicationsJun 29 2009Oct 27 2009Our preceding paper introduced a method to compute Casimir forces in arbitrary geometries and for arbitrary materials that was based on a finite-difference time-domain (FDTD) scheme. In this manuscript, we focus on the efficient implementation of our ... More Optimal nanoparticle forces, torques, and illumination fieldsMay 29 2018Dec 21 2018A universal property of resonant subwavelength scatterers is that their optical cross-sections are proportional to a square wavelength, $\lambda^2$, regardless of whether they are plasmonic nanoparticles, two-level quantum systems, or RF antennas. The ... More Power--bandwidth limitations of an optical resonanceOct 23 2015We present shape-independent upper limits to the power--bandwidth product for a single resonance in an optical scatterer, with the bound depending only on the material susceptibility. We show that quasistatic metallic scatterers can nearly reach the limits, ... More Casimir micro-sphere diclusters and three-body effects in fluidsDec 03 2010Apr 13 2011Our previous article [Phys. Rev. Lett. 104, 060401 (2010)] predicted that Casimir forces induced by the material-dispersion properties of certain dielectrics can give rise to stable configurations of objects. This phenomenon was illustrated via a dicluster ... More Ingredients of a Casimir analog computerMar 03 2009Mar 09 2009We present the basic ingredients of a technique to compute quantum Casimir forces at micrometer scales using antenna measurements at tabletop, e.g. centimeter, scales, forming a type of analog computer for the Casimir force. This technique relies on a ... More Geometry-induced Casimir suspension of oblate bodies in fluidsOct 16 2013We predict that a low-permittivity oblate body (disk-shaped object) above a thin metal substrate (plate with a hole) immersed in a fluidof intermediate permittivity will experience a meta-stable equilibrium (restoring force) near the center of the hole. ... More General Theory of Spontaneous Emission Near Exceptional PointsApr 21 2016Sep 19 2016We present a general theory of spontaneous emission at exceptional points (EPs)---exotic degeneracies in non-Hermitian systems. Our theory extends beyond spontaneous emission to any light--matter interaction described by the local density of states (e.g., ... More Interaction-induced mode switching in steady-state microlasersApr 29 2015Jan 22 2016We demonstrate that due to strong modal interactions through cross-gain saturation, the onset of a new lasing mode can switch off an existing mode via a negative power slope. In this process of interaction-induced mode switching (IMS) the two involved ... More Perfect Single-Sided Radiation and Absorption without MirrorsJul 16 2016Sep 22 2016Highly directional radiation from photonic structures is important for many applications, including high power photonic crystal surface emitting lasers, grating couplers, and light detection and ranging devices. However, previous dielectric, few-layer ... More General Theory of Spontaneous Emission Near Exceptional PointsApr 21 2016May 18 2017We present a general theory of spontaneous emission at exceptional points (EPs)---exotic degeneracies in non-Hermitian systems. Our theory extends beyond spontaneous emission to any light--matter interaction described by the local density of states (e.g., ... More Evanescent-Wave Bonding Between Optical WaveguidesSep 09 2005Forces arising from overlap between the guided waves of parallel, microphotonic waveguides are calculated. Both attractive and repulsive forces, determined by the choice of relative input phase, are found. Using realistic parameters for a silicon-on-insulator ... More Symmetry, stability, and computation of degenerate lasing modesNov 05 2016We present a general method to obtain the stable lasing solutions for the steady-state ab-initio lasing theory (SALT) for the case of a degenerate symmetric laser in two dimensions (2d). We find that under most regimes (with one pathological exception), ... More Symmetry, stability, and computation of degenerate lasing modesNov 05 2016Feb 25 2017We present a general method to obtain the stable lasing solutions for the steady-state ab-initio lasing theory (SALT) for the case of a degenerate symmetric laser in two dimensions (2d). We find that under most regimes (with one pathological exception), ... More Measures on transitions for cosmology from eternal inflationDec 19 2006May 04 2007We argue that in the context of eternal inflation in the landscape, making predictions for cosmological -- and possibly particle physics -- observables requires a measure on the possible cosmological histories as opposed to one on the vacua themselves. ... More Hurdles for Recent Measures in Eternal InflationNov 21 2006Mar 23 2007In recent literature on eternal inflation, a number of measures have been introduced which attempt to assign probabilities to different pocket universes by counting the number of each type of pocket according to a specific procedure. We give an overview ... More