Regularization of vertical-cavity surface-emitting laser emission by periodic non-Hermitian potentials

Abstract

We propose a novel physical mechanism based on periodicnon-Hermitian potentials to efficiently control the complexspatial dynamics of broad-area lasers, particularly in vertical-cavity surface-emitting lasers (VCSELs), achieving a stableemission of maximum brightness. A radially dephased peri-odic refractive index and gain-loss modulations accumulatethe generated light from the entire active layer and concen-trate it around the structure axis to emit narrow, brightbeams. The effect is due to asymmetric inward radial cou-pling between transverse wave vectors for particular phasedifferences of the refractive index and gain-loss modulations.Light is confined into a central beam with large intensity,opening the path to design compact, bright, and efficientbroad-area light sources. We perform a comprehensive analy-sis to explore the maximum central intensity enhancement andconcentration regimes. This Letter reveals that the optimumschemes are those holding unidirectional inward coupling,but not fulfilling a perfect local PT-symmetry.