Mid-infrared upconversion spectroscopy

Abstract

Mid-infrared (MIR) spectroscopy is emerging as an attractive alternative to near-infrared or visible spectroscopy. MIR spectroscopy offers a unique possibility to probe the fundamental absorption bands of a large number of gases as well as the vibrational spectra of complex molecules. In this paper we discuss non-collinear upconversion as a means for obtaining MIR spectra in the 5–10 μm range with a resolution better than 20 cm−1 over the full interval using four discrete phase-match settings. A theoretical treatment of non-collinear upconversion is given and two different experimental implementations are tested.