Sensitive dependence of the linewidth enhancement factor on electronic quantum effects in quantum cascade lasers
نویسندگان
چکیده
The linewidth enhancement factor (LEF) describes the coupling between amplitude and phase fluctuations in a semiconductor laser, has recently been shown to be crucial component for frequency comb formation addition broadening. It necessarily arises from causality, as famously formulated by Kramers-Kronig relation, media with non-trivial dependence of susceptibility on intensity variations. While thermal contributions are typically slow, thus can often excluded suitably designing dynamics an experiment, many quantum harder separate. In order understand and, ultimately, design LEF suitable values formation, soliton generation, or narrow laser linewidth, it is therefore important systematically model all these effects. this comprehensive work, we introduce general scheme computing LEF, which employ non-equilibrium Green's function model. This direct method, based simulating system response under varying optical intensity, extracting fluctuations, include relevant electronic effects predicts operating cascade range 0.1 - 1, depending bias frequency. We also confirm that many-body effects, off-resonant transitions, dispersive (Bloch) gain, counter-rotating terms, intensity-dependent transition energy, precise subband distributions significantly contribute accurate simulations LEF.
منابع مشابه
Importance of the microscopic effects on the linewidth enhancement factor of quantum cascade lasers.
Microscopic density matrix analysis on the linewidth enhancement factor (LEF) of both mid-infrared (mid-IR) and Terahertz (THz) quantum cascade lasers (QCLs) is reported, taking into account of the many body Coulomb interactions, coherence of resonant-tunneling transport and non-parabolicity. A non-zero LEF at the gain peak is obtained due to these combined microscopic effects. The results show...
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ژورنال
عنوان ژورنال: Applied Physics Letters
سال: 2023
ISSN: ['1520-8842', '0003-6951', '1077-3118']
DOI: https://doi.org/10.1063/5.0111599