Fast-sweeping continuous wave quantum cascade laser operating in an external cavity with polygon mirror

We report a continuous wave room temperature quantum cascade laser operating in an external cavity in the Littrow configuration with a 10-facet polygon mirror rotating at 24,000 RPM. The quantum cascade laser emission is swept across similar to 1520 - 1625 cm(-1) wavenumber range in less than similar to 45 mu s with a sweep repetition rate of 4 kHz. The measured maximum output power at the laser gain maximum, 15 degrees C and 0.86 A driving current is similar to 90 mW; the estimated average output power across the 45 mu s wavenumber sweep is similar to 50 mW. Through its sweep, the laser emits on the sequential Fabry-Perot longitudinal modes of the laser chip cavity with the mode separation of similar to 0.5 cm(-1). The linewidth of the emitting modes is less than similar to 0.05 cm(-1). Spectral measurements of the infrared absorption features of a 10 mu m thick layer of acetophenone and water vapor in the air have demonstrated the capability of obtaining spectral data in less than 45 mu s. Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License.