Abstract

We report on the development and performance of a high power, widely tunable, continuous wave external cavity quantum cascade laser (EC-QCL) designed for infrared vibrational spectroscopy of molecules exhibiting broadband and single line absorption features [1]. The laser is characterized and applied to high resolution spectroscopy and wide tunability for trace gas detection in the mid infrared wavelength region between 7 and 8.8 µm. The laser source exhibits single mode operation with a tunability up to 303 cm⁻¹ (~ 24% of the center wavelength) at 8 µm, with a maximum optical output power of 200 mW. In combination with off-axis integrated output spectroscopy, trace-gas detection of broadband absorption gases such as acetone was performed and a noise equivalent absorption sensitivity of NEAS = 3.7 · 10⁻⁸ cm⁻¹ Hz^−1/2 was obtained.

© 2015 IEEE