Abstract

Difference frequency mixing (DFM) of a Raman shifted beam with the fundamental pump beam was first demonstrated in 1966.¹ Subsequently difference frequency mixing of 2 laser sources was applied to molecular spectroscopy.² More recently remote sensing of molecular gasses has been accomplished using optical parametric oscillators.³ We demonstrate the application of DFM of a Raman shifted beam to remote sensing of methane. This scheme has two key advantages: it uses a single pump source and does not require a frequency reference.

© 1995 IEEE