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Multi-frequency Raman generation or cascaded four wave mixing


At Waterloo, we are studying Multi-frequency Raman generation, which efficiently generates a large number of Raman orders spanning the spectral region from infrared to ultraviolet. This research is motivated by the need for a high-intensity, sub-5 fs pulse source for Coulomb explosion imaging and spectroscopy. In this talk, I will discuss our experimental results showing that the spectrum is predominantly on the anti-Stokes side and that with improved phase matching, the peak of the spectrum moves to higher frequencies. I will also discuss our recent experimental results showing that by varying the time between the two chirped pump pulses, we can change the resulting spectra of the individual orders.  The intensity of the higher orders can actually be improved when the separation of the spectral orders moves from being separated by the Raman transition to being separated by the pump frequency separation.