A frequency stabilized tunable pulsed quantum cascade laser

We report on a method and circuits for frequency stabilization of a pulsed quantum cascade laser (QCL). The proposed method allows stabilizing the laserpsilas absolute frequency as well as its tuning range. Three different experimental layouts are tested. In all three layouts an absorption cell is used for absolute frequency reference. A Germanium Fabry-Perot etalon is used for tuning range stabilization. The distance between the first and last maxima of the interference fringes is used to produce a signal, which controls the tuning range of the laser. This signal is applied to the QCL pulse driver. The stabilities achieved of the absolute frequency (F₀) and sweeping range (DeltaF) are close to 30 MHz @ F₀=30 THz and DeltaF=40 GHz respectively. These stabilities are mainly limited by the discrimination time of 100 ps of our digital oscilloscope.