Abstract

We exploit the first-order interference of two frequency non-degenerate Parametric Down Conversion (PDC) sources to observe resonant absorption of CO₂ gas. Frequency correlations of PDC modes allow the detection of resonant absorption and dispersion of the infrared (IR) mode from interference patterns of visible light. This work demonstrates the determination of real and imaginary parts of the refractive index for IR wavelengths with conventional visible range optics and photodetectors.

© 2015 Optical Society of America