We present a demonstration of mid-infrared photon echoes generated with parametrically downconverted incoherent light. The photon echoes generated in this way enable one to study the dynamics of vibrations in the 1.5-4.0 -μm wavelength region with subpicosecond time resolution.

Opt. Lett.
Ultrafast Spectroscopy

Woutersen, S., Bonn, M., Brugmans, M. J. P., Emmerichs, U., & Bakker, H. (1996). Generation of incoherent mid-infrared photon echoes with parametrically downconverted light. Opt. Lett., 21, 1579–1581.