Abstract
We propose and explore a physical mechanism for the stabilization of the complex spatiotemporal dynamics in arrays (bars) of broad area laser diodes taking advantage of the symmetry breaking in non-Hermitian potentials. We show that such stabilization can be achieved by specific pump and index profiles leading to a PT-symmetric coupling between nearest neighboring lasers within the semiconductor bar. A numerical analysis is performed using a complete (2 + 1)-dimensional space-temporal model, including transverse and longitudinal spatial degrees of freedom and temporal evolution of the electric field and carriers. We show regimes of temporal stabilization and light emission spatial redistribution and enhancement. We also consider a simplified (1 + 1)-dimensional model for an array of lasers holding the proposed non-Hermitian coupling with a global axisymmetric geometry. We numerically demonstrate a two-fold benefit: the control over the temporal dynamics over the EELs bar and the field concentration on the central lasers leading to a brighter output beam, facilitating a direct coupling to an optical fiber.
Highlights
Diode lasers systems, either in the form of a single Edge-Emitting Laser (EEL), in the form of arrays of lasers, or as stacks of EEL bars, are replacing other lasers sources due to their compactness, affordable prices and high performance
In order to model the spatial redistribution and temporal stabilization of coupled EEL sources, we use a well-established model including the spatiotemporal evolution of the electromagnetic field and carrier density inside the cavity [20]
The results show a Hopf bifurcation arising at a particular pump, referred as the Hopf pump, pH, and for pump values above this threshold the laser becomes temporally unstable as it is evident comparing the temporal evolution of the spatial distribution transverse profile for two given pump values below and above pH, sharing monomode spatial distribution along the laser
Summary
Either in the form of a single Edge-Emitting Laser (EEL), in the form of arrays of lasers (lasers bars), or as stacks of EEL bars, are replacing other lasers sources due to their compactness, affordable prices and high performance. Introduced as a curiosity in quantum mechanics [21], parity-time (PT-) symmetry, found experimental realizations in the field of photonics in artificial materials with spatial distributions of real and complex permittivities, showing the ability of molding the flow of light [22,23,24,25,26] The attentions to those systems that while being non-conservative could still hold real energy eigenvalues, derives from the unusual, even counter intuitive properties they hold arising from an asymmetric coupling of modes. The light generated in every single semiconductor laser is expected to be spatially redistributed and temporally stabilized via non-Hermitian coupling between neighboring lasers induced by a particular gain (pump) and index modulation (stripes) of the structure. A simplified (1 + 1)-dimensional model is used to extend the study to a full EEL bar formed by an array of many lasers The simulations show both temporal stabilization and simultaneous spatial redistribution, i.e. localization, of the generated light
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