Low-Threshold RNGH Instabilities in Quantum Cascade Lasers

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Vuković, Nikola N.
Radovanović, Jelena
Milanović, Vitomir
Boiko, Dmitri L.
We show that low-threshold Risken-Nummedal-Graham-Haken (RNGH) instabilities in quantum cascade lasers (QCLs) occur due to a combined effect of the carrier coherence and population grating induced in the gain medium. QCLs with a few mm long cavity exhibit intermittent RNGH self-pulsations while regular self-pulsations are possible in short-cavity QCLs, with the cavity length of 100 ?m or smaller. Transient behavior to RNGH self-pulsations in short-cavity QCLs shows features resembling cooperative superradiance which opens a practical way of achieving ultrashort pulse production regimes in the mid-infrared spectral range.
Publication Reference
IEEE Journal of Selected Topics in Quantum Electronics, vol. 23 (6), pp. 1-16