Wolf effect in the scattering of polychromatic radiation by two spheres having parity-time symmetry

Abstract

It was recently proposed (P A Brandão and S B Cavalcanti 2019 Phys. Rev. A 100 043822) that two small (Dirac) scatterers, one having gain and the other having loss, drastically modifies the spectral density of the scattered radiation field. Here, we extend this previous work by studying the scattering of stochastic radiation by two finite spheres having gain and loss, satisfying the parity-time symmetry condition, and verifying the spectral changes in frequency domain, i.e. the non-Hermitian Wolf effect. Under the Born approximation, we analytically found the specific frequencies where the spectral density of the scattered field vanishes and show that they depend on the gain and loss parameter γ of each material. This is evidence of a non-Hermitian Wolf effect, meaning that the spectrum can be tuned by the gain/loss properties of the system. We have also shown that there is a π/2 phase shift when compared to the Hermitian configuration (γ = 0).