Incoherent Raman spectroscopy is a widely used tool in physical and chemical science. Coherent Raman spectroscopy, e.g. CARS (coherent anti-Stokes Raman scattering) on the other hand has not been as widely adopted. One reason for this is the well-known 'nonresonant background' originating from both solvent and target molecules, due to the instantaneous electronic response and multiple off-resonant vibrational modes. However, with the advent of short and ultrashort pulsed lasers the CARS technique is now being applied to microscopy and the detection of anthrax-type endospores via various extensions of coherent spectroscopy. With such applications in mind, a simple physical picture of CARS spectroscopy is presented, having much in common with Dicke superradiance. Recent work is discussed that provides an effective method for mitigation of the background noise.
