Theoretical approach to quantum cascade micro-laser broadband multimode emission in strong magnetic fields

We have theoretically explored the influence of the magnetic field on supporting the multimode Risken-Nummendal-Graham-Haken (RNGH) self-pulsations seen in the optical spectrum as two broad modulations sidebands at the Rabi flopping frequency [25-27]. On the example of microcavity quantum cascade lasers (mu-QCLs), we demonstrate that Landau quantization in an external magnetic field slows down the effective decoherence and diffusion rates. The pump current required to reach the broadband multimode RNGH self-pulsations is lowered with the magnetic field strength, while the Rabi flopping frequency and the overall optical spectrum width remain practically unchanged. Our theoretical results indicate that an external magnetic field can be a valuable tool for achieving high-power broadband QCL self-pulsations in practice. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the influence of a magnetic field on multimode self-pulsations, revealing that an external magnetic field can slow down decoherence and diffusion rates in quantum cascade lasers, reducing the pump current required to achieve self-pulsations. As the magnetic field strength increases, the self-pulsation frequency and spectrum width remain practically unchanged.