We report on the wavelength tuning dynamics in continuous-wave distributed feedback quantum cascade lasers (QCLs). The wavelength tuning response for direct current modulation of two mid-IR QCLs from different suppliers was measured from 10 Hz up to several MHz using ro-vibrational molecular resonances as frequency-to-intensity converters. Unlike the output intensity, which can be modulated up to several gigahertz, the frequency-modulation bandwidth was found to be on the order of 200 kHz, limited by the laser thermal dynamics. A non-negligible roll-off and a significant phase shift are observed above a few hundred hertz already and explained by a thermal model.
Wavelength tuning and thermal dynamics of continuous-wave mid-infrared distributed feedback quantum cascade lasers
Lionel Tombez, Francesco Cappelli, Stéphane Schilt, Gianni Di Domenico, Saverio Bartalini, Daniel Hofstetter; Wavelength tuning and thermal dynamics of continuous-wave mid-infrared distributed feedback quantum cascade lasers. Appl. Phys. Lett. 15 July 2013; 103 (3): 031111. https://doi.org/10.1063/1.4813753
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