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Journal articles
Extensive study of the linewidth enhancement factor of a distributed feedback quantum cascade laser at ultra-low temperature
Abstract : Quantum cascade lasers (QCLs) are optical sources exploiting radiative intersubband transitions within the
conduction band of semiconductor heterostructures. The opportunity given by the broad span of wavelengths
that QCLs can achieve, from mid-infrared to terahertz, leads to a wide number of applications such as absorption
spectroscopy, optical countermeasures and free-space communications requiring stable single-mode operation
with a narrow linewidth and high output power. One of the parameters of paramount importance for studying
the high-speed and nonlinear dynamical properties of QCLs is the linewidth enhancement factor (LEF). The
LEF quanti es the coupling between the gain and the refractive index of the QCL or, in a similar manner, the
coupling between the phase and the amplitude of the electrical fi eld. Prior work focused on experimental studies
of the LEF for pump currents above threshold but without exceeding 12% of the threshold current at 283K
and 56% of the threshold current at 82K. In this work, we use the Hakki-Paoli method6 to retrieve the LEF for
current biases below threshold. We complement our ndings using the self-mixing interferometry technique to
obtain LEFs for current biases up to more than 100% of the threshold current. These insets are meaningful to
understand the behavior of QCLs, which exhibit a strongly temperature sensitive chaotic bubble when subject
to external optical feedback.
Cited literature [35 references]
https://hal.telecom-paris.fr/hal-02342862
Contributor : Olivier Spitz <>
Submitted on : Monday, November 11, 2019 - 4:50:43 PM
Last modification on : Wednesday, October 14, 2020 - 4:14:37 AM
Long-term archiving on: : Wednesday, February 12, 2020 - 2:26:19 PM
Contributor : Olivier Spitz <>
Submitted on : Monday, November 11, 2019 - 4:50:43 PM
Last modification on : Wednesday, October 14, 2020 - 4:14:37 AM
Long-term archiving on: : Wednesday, February 12, 2020 - 2:26:19 PM
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