Scattering of polaritons by point defects in spatially dispersive media

Abstract

For a simple model, we study the scattering of a polariton from a static point defect, in the presence of spatial dispersion. The polariton is scattered elastically by the defect, and in analogy with the theory of the reflection of light from the surface of a spatially dispersive medium, there are several final states possible. For example, when the medium is isotropic (the case considered here), an incident transverse polariton scatters into two transverse polariton final states, and into a longitudinal polariton final state upon striking the defect. The contributions to the cross section from these various scattering processes has been evaluated numerically, for a simple model and parameters appropriate to GaP in the infrared.

Energy-Transport, Group, and Signal Velocities near Resonance in Spatially Dispersive Media

“…5 Notice that j = 1 and j = 2 correspond to upper polariton (UP) and lower polariton (LP), respectively. The energy flux vector S in a spatially dispersive medium has been shown by Maddox and Mills, 6 and Bishop and Maradudin, 2 to be the sum of an electromagnetic Poynting vector S E = (c/47r)E XH and a "mechanical" (in our case excitonic) Poynting vector S^, both of which contribute to the energy transport. We now follow Ref.…”

Optical current, momentum and angular momentum in anisotropic materials exposed to detailed balance

“…Optical forces induced by time-dependent electromagnetic fields appear in Eq. (17). However, an optical "Abraham force" proportional to gV dB/dt does not show up in Eq.…”

“…In homogeneous, conservative and local dielectric media the Poynting vector is parallel to the group velocity [16] which excludes the well-known ambiguity to add any curl of a vector field to the Poynting vector to describe the energy current [8]. Only when we would allow spatial dispersion explicitly in the dielectric tensor ε(k), the Poynting vector fails to describe the energy current, and an additional contribution proportional to (∂ k ε nm )E nĒm from the material enters the energy current density [17,18].…”

“…However, an optical "Abraham force" proportional to gV dB/dt does not show up in Eq. (17) and is here generated by the presence of the radiation noise. If we would apply the above formula for K to the quantum vacuum (Q =hω), using that at high frequencies V (ω) ∼ 1/ω 2 if the Verdet constant V is associated with the microscopic Zeeman shift of atomic levels, and similarly g(ω) ∼ 1/ω 2 if g is associated with a simultaneous magnetic and electric dipole transition in a chiral molecule [19], the frequency integral does not seem to suffer from an ultraviolet catastrophe.…”

Local polariton states in polar crystals with impurities

“…This relaxation-induced threshold can be estimated from Eq. (14) provided that the threshold is small enough that calculations of the integral in the main singular approximation still valid:…”