Quantum cascade lasers (QCLs) are an emerging solution for a wide variety of molecular spectroscopy applications, but for many of these applications, wavelength tuning accuracy and repeatability are essential to successful deployment. Tunability has typically been achieved either through current tuning of DFB lasers, which yields very narrow but precise tuning, or through grating-based tuning of Fabry-Perot lasers, which yields broad spectral coverage but with less wavelength accuracy and stability. We describe the development and application of a new tunable external cavity QCL platform utilizing MEMS fabricated tunable thin film filters which achieve both a broad tuning range and precise wavelength control. This platform is enabling the use of QCLs for both high resolution gas phase spectroscopy of multiple analytes and high sensitivity condensed phase measurements.
© 2014 Optical Society of AmericaPDF Article