Stabilized narrow-beam emission from broad-area semiconductor lasers
Judith Medina Pardell, R. Herrero, Muriel Botey, Kęstutis Staliūnas
Abstract
We provide a feasible and compact scheme to control and stabilize the spatiotemporal dynamics of broad-area semiconductor (BAS) lasers. The proposal is based on the ability of non-Hermitian potentials with given local symmetries to manage the flow of light. A local PT-symmetric configuration allows controlling, enhancing, and localizing the generated light. We impose a pump modulation, with a central symmetry axis which induces in-phase gain and refractive index modulations due to the Henry factor. Both modulations are, in turn, spatially dephased by an appropriate index profile to yield to a local PT symmetry within the modified BAS laser. Such local PT-symmetry potential induces an inward mode coupling, accumulating the light generated from the entire active layer at the central symmetry axis, which ensures spatial regularization and temporal stability. By an exhaustive exploration of the modulation parameters, we show a significant improvement of the intensity concentration, stability, and brightness of the emitted beam. This approach produces a twofold benefit: light localization into a narrow-beam emission and the control over the spatiotemporal dynamics, improving the laser performance.