Counterposed phase velocity and energy-transport velocity vectors in a dielectric-magnetic uniaxial medium

When a plane wave is launched from a plane surface in a linear, homogenous, dielectric-magnetic, uniaxial medium, we show that its phase velocity and the energy-transport velocity vectors can be counterposed (i.e., lie on different sides of the surface normal) under certain circumstances.Comment: 3 figure

Reverse Circular Bragg Phenomenon

The axial propagation of circularly polarized light in an optically active structurally chiral medium is exactly solved via full electromagnetic analysis. Some symmetries of the system's characteristic matrix reveal new insights, which are confirmed by coupled wave theory. For extreme values of chirality, now accessible via metamaterials, a reverse circular Bragg resonance arises in the negative refraction regime where handedness reversal of counterpart modes occurs. A condition is identified under which optical activity offsets structural chirality, rendering the medium simply birefringent.Comment: 14 pages, 6 figure

Electromagnetism, Axions, and Topology:a first-order operator approach to constitutive responses provides greater freedom

We show how the standard constitutive assumptions for the macroscopic Maxwell equations can be relaxed. This is done by arguing that the Maxwellian excitation fields (D, H) should be dispensed with, on the grounds that they (a) cannot be measured, and (b) act solely as gauge potentials for the charge and current. In the resulting theory, it is only the links between the fields (E, B) and the charge and current (ρ, J ) that matter; and so we introduce appropriate linear operator equations that combine the Gauss and Maxwell-Ampère equations with the constitutive relations, eliminating (D, H). The result is that we can admit more types of electromagnetic media – notably, the new relations can allow coupling in the bulk to a homogeneous axionic material; in contrast to standard EM where any homogeneous axion-like field is completely decoupled in the bulk, and only accessible at boundaries. We also consider a wider context, including the role of topology, extended non-axionic constitutive parameters, and treatment of Ohmic currents. A range of examples including an axionic response material is presented, including static electromagnetic scenarios, a possible metamaterial implementation, and how the transformation optics paradigm would be modified. Notably, these examples include one where topological considerations make it impossible to model using (D, H)

Catapult Description of Magnetic Fields and Forces

In many high school teaching materials the force on a current-carrying wire in a magnetic field is discussed using an idea based on a so-called “catapult field” (cf. Fig. 1), an engaging depiction of magnetic forces, albeit one which, to the best of our knowledge, has neither been used in college-level educational material or scrutinized in academic journals. Here we examine carefully the physical basis of the “catapult field” concept, and find both its accuracy and utility seriously questionable

The negative index of refraction demystified

We study electromagnetic wave propagation in mediums in which the effective relative permittivity and the effective relative permeability are allowed to take any value in the upper half of the complex plane. A general condition is derived for the phase velocity to be oppositely directed to the power flow. That extends the recently studied case of propagation in mediums for which the relative permittivity and relative permeability are both simultaneously negative, to include dissipation as well. An illustrative case study demonstrates that in general the spectrum divides into five distinct regions.Comment: 5 pages, 4 figure