Subdiffraction and spatial filtering due to periodic spatial modulation of the gain/loss profile

TL;DR

This paper explores how periodic gain/loss modulation in materials can lead to diffraction-free beam propagation and spatial filtering, with predictions supported by numerical simulations of wave equations.

Contribution

It introduces a novel analysis of 2D gain/loss modulated media predicting self-collimation and superdiffusion effects, supported by numerical validation.

Findings

Self-collimation of beams in modulated media

Superdiffusion and spatial filtering effects

Numerical simulations confirm theoretical predictions

Abstract

We investigate light propagation through materials with periodically modulated gain/loss profile in both transverse and longitudinal directions, i.e. in material with two-dimensional modulation in space. We predict effects of self-collimation (diffraction-free propagation) of the beams, as well as superdiffusion (spatial frequency filtering) of the beams in depending on the geometry of the gain/loss lattice, and justify the predictions by numerical simulations of the paraxial wave propagation equations.