Spectral Dynamics of Quantum Cascade Lasers Generating Frequency Combs in the Long-Wavelength Infrared Range.

We have studied the spectral and dynamic characteristics of quantum cascade lasers emitting in the long-wavelength infrared range. It is shown that lasers with a short cavity (~1 mm) make it possible to obtain frequency combs in a very wide spectral range. We have investigated the spectral dynamics in the frequency comb generation regime. It is demonstrated that the intensity of longitudinal laser modes varies during a pump pulse propagation. We have observed simultaneous generation of all longitudinal modes of a frequency comb over a pump pulse segment with a constant amplitude. [ABSTRACT FROM AUTHOR]