High-resolution four-photon spectroscopy with chirped pulses

We propose new schemes of high-resolution coherent four-photon spectroscopy where chirped pulses are employed for the Raman excitation of a nonlinear medium. The use of linearly chirped pulses in coherent anti-Stokes Raman scattering spectroscopy allows the spectra of nonlinear susceptibility to be studied with a terahertz resolution by measuring the intensity of the signal emerging from four-wave mixing as a function of the delay time between the pump pulses. This approach can be also employed for single-pulse spectroscopy of nonlinear susceptibility.