Low-frequency fluctuations of a mid-infrared quantum cascade laser operating at cryogenic temperatures

This work demonstrates that mid-infrared quantum cascade lasers operating under external optical feedback can output a chaotic dynamics through low-frequency fluctuations close to 77 K. Results also show that the birth of chaotic dynamics is not limited to near-threshold pumping levels. In addition, when the semiconductor material is cooled down from room temperature to 77 K, it is found that laser destabilization takes place at a lower feedback ratio, proving that quantum cascade lasers are sensitive to temperature, likely due to changes in the upper state lifetime. These investigations are meaningful for the chaotic operation of quantum cascade lasers in secure atmospheric transmission lines and optical countermeasure systems.