Abstract:
The frequency tuning of a pulsed single-frequency quantum cascade laser with U-shaped cavity was studied when the temperature varied from 300 to 10 K in the wavelength range 7.7–7.5 $\mu$m, amounting to about 35 cm$^{-1}$. The tuning of the laser frequency $\Delta\nu\sim$ 1 cm$^{-1}$ was demonstrated in a time of about 50 ns during a laser power pulse. When the laser radiation frequency was swept during a pulse at room temperature, an absorption line of water vapor in the atmosphere was observed at a frequency of 1296.7 cm$^{-1}$.
Keywords:quantum cascade laser, U-shaped cavity, frequency tuning, water vapor absorption.