Directive emission of red conjugated polymer embedded within zero index metamaterials

Abstract: We numerically demonstrate an impedance-matched multilayer stacked fishnet metamaterial that has zero index with flat high transmittance from 600nm to 620nm. The effective refractive index

Plasmonic nanogaps for broadband and large spontaneous emission rate enhancement

We present the optical properties of a plasmonic nanogap formed between a silver metallic nanoparticle and an extended silver film that shows a strong enhancement in the spontaneous emission rate over the whole visible range. In particular, we use three-dimensional finite difference time domain calculations to study the spontaneous emission rate and the quantum efficiency of an emitting material placed within the gap region as a function of the geometrical parameters of the plasmonic nanogap. Our calculations reveal that the enhancements in the total decay rate can be divided into two regions as a function of wavelength; region I spans the wavelength range from 350 nm to 500 nm and peaks at approximately at 400 nm. Region II covers the spectral range between 500 nm and 1000 nm. The enhancements in total decay rate in region I are mainly dominated by Ohmic losses by the metal, while the enhancements in total decay rate in region II are mainly dominated by radiative decay rate enhancements. Furthermore, our calculations show over 100 times enhancement in the spontaneous emission rate in region II. We combine this with quantum efficiency enhancements of almost 30 times from materials with low intrinsic quantum efficiencies and only a small reduction in efficiency from those with high intrinsic quantum efficiencies. All results appear easily achievable using realistic geometrical parameters and simple synthesis techniques. These results are attributed to the strong field confinements in the nanogap region. The structures are of high interest for both the fundamental understanding of light mater interactions under extreme electromagnetic field confinements and also potential applications in quantum optics and Raman spectroscopy

Shear and Peel Stresses at the Interface between Hollowcore Slabs and the Topping Concrete

Hollowcore slabs are used in floors and roofs of residential, commercial, industrial and institutional buildings. They are precast/prestressed concrete elements produced using the extrusion process. Their surface finish can be “machine-cast” or “intentionally roughened”. A typical floor consists of a number of hollowcore slabs that are connected together. Prestressing causes hollowcore slabs to camber, which results in an uneven floor surface. A 50 mm topping concrete is commonly cast to level the floor surface. To avoid delamination, engineers require bonding agents to be applied on the hollowcore slab surface before pouring the topping concrete. The concrete topping can be used compositely with the hollowcore slabs to increase the floor’s load carrying capacity. However, North American design standards require intentional roughening of the hollowcore slab surface to consider such composite action. This requirement results in added cost that manufacturers are keen to avoid. This thesis presents a comprehensive experimental program to assess the performance of composite hollowcore slabs with machine-cast and lightly-roughened surface finishes. Three types of tests were performed: pull-off, push-off and full-scale. They provided an overall understanding of the interfacial shear and peel behaviors at the interface between hollowcore slabs and the topping concrete. The tested slabs were found to sustain higher interfacial shear stresses than the limits set by the design standards and to provide adequate composite behavior up to failure. Linear analytical modeling in which closed-form solutions for differential equations governing the interfacial shear and peel stresses during the push-off tests was conducted. Two analytical methods were developed to estimate the shear and peel stresses during the full-scale tests utilizing the interface stiffness determined from the pushoff tests. Linear finite element analysis was performed to validate and compare the proposed methods. To better understand the experimental results and to provide engineers with more accurate tools for estimating the interfacial stresses, nonlinear finite element analysis of the push-off and the full-scale tests were conducted. Interfacial shear and peel stiffness values associated with the tested slabs were also determined to assist design engineers in predicting failure modes of composite hollowcore slab

Algebraic structures on parallel M2-branes

In the course of closing supersymmetry on parallel M2 branes up to a gauge transformation, following the suggestion in hep-th/0611108 of incorporating a gauge field which only has topological degrees of freedom, we are led to assume a certain algebraic structure for the low energy theory supposedly living on parallel M2 branes.Comment: 13 pages; v4: complete on-shell closure of supersymmetry, abstract changed, v5: gauge transformations are carefully define

Interaction Of Electric And Magnetic Charges: Addendum

The problem of a head-on collision between a spherically symmetric electric and magnetic charge is reconsidered. The assumption of the equality of the electric and magnetic forces made earlier is abandoned as it does not follow from the model. It is shown that the rotational angular momentum a charge acquires is determined by the amount of the angular momentum which the charge removes from the field by virtue of its extension. The interaction energy of each charge with the dipole it induces in the other charge is equal to the rotational energy of the charge itself. This results in simple expressions for the effective potential, and the distance of closest approach as given by classical electrodynamics and nonrelativistic mechanics. A mechanism is suggested for the transfer of the angular momentum from the field to the monopole. © 1985 The American Physical Society

Thomson\u27s Monopoles

The angular momentum L of the electromagnetic field due to an electric point charge e, and a magnetic point charge (pole) g, is calculated by several methods to obtain J. J. Thomson\u27s result that L = eg/c, and L is directed along the line joining the electric monopole to the magnetic monopole. The relation to Dirac\u27s monopoles is discussed, and particle size is considered. © 1991, American Association of Physics Teachers. All rights reserved

Interaction Of Electric And Magnetic Charges

It is shown classically that in a head-on collision between an electric and a magnetic charge a repulsive polarization force of the form r-5 results (where r is the distance between the charges), if one (both) charge(s) is (are) assigned a finite spherical size. This force leads to a minimum distance of approach and prevents one particle from going through the other, and thus guards against the violation of the conservation of angular momentum. This polarization force is a manifestation of the diamagnetism (diaelectricity) of extended electric (magnetic) charges. © 1977 The American Physical Society