Four-wave mixing with broad beams: The feasibility of single-pulse time-resolved measurements and chirped-pulse Raman spectroscopy

We propose new schemes of high-resolution coherent four-photon spectroscopy where noncollinear broad pump beams are used for the Raman excitation of a nonlinear medium. Such schemes allow single-pulse time-resolved measuremen ts on the nonlinear response of a spatially uniform medium to be performed by imaging the spatial intensity profile in a broad beam generated through the four-wave mixing process. The use of lineal ly chirped pulses in cohere nt nonlinear Raman spectroscopy with noncollinear broad beams permits the s pectra of nonlinear susceptibility to be measured with a high (subterahertz ) resolution in spatially uniform media by single-pulse imaging of the spat ial profile of the four-wave mixing signal.