High-Directional Wave Propagation in Periodic Gain/Loss Modulated Materials

TL;DR

This paper demonstrates through numerical simulations that two-dimensional periodic gain/loss materials exhibit high directional anisotropy in wave amplification and attenuation, enabling effective filtering of high spatial harmonics.

Contribution

It provides the first numerical proof of high anisotropy in gain/loss in 2D periodic structures with square and rhombic lattices, revealing potential for wave filtering applications.

Findings

High anisotropy of gain/loss in 2D periodic structures

Narrowing of the angular spectrum of propagating waves

Potential for filtering high spatial harmonics

Abstract

Amplification/attenuation of light waves in artificial materials with a gain/loss modulation on the wavelength scale can be sensitive to the propagation direction. We give a numerical proof of the high anisotropy of the gain/loss in two dimensional periodic structures with square and rhombic lattice symmetry by solving the full set of Maxwell's equations using the finite difference time domain method. Anisotropy of amplification/attenuation leads to the narrowing of the angular spectrum of propagating radiation with wavevectors close to the edges of the first Brillouin Zone. The effect provides a novel and useful method to filter out high spatial harmonics from noisy beams.