Wideband frequency modulation spectroscopy using the quantum cascade laser

Summary form only given. The quantum cascade (QC) laser is a promising new source for tunable, infrared laser radiation and the spectroscopic capabilities of the QC laser were recently demonstrated. In this report, we extend previous work by demonstrating wideband frequency modulation (FM) of the QC laser and the detection of FM spectroscopic signals from a weakly absorbing sample of molecules.