A frequency modulation coherent antihyphen;Stokes Raman spectroscopy (FMhyphen;CARS) is proposed. Using phasehyphen;modulated Stokes input field, a frequency modulated CARS output is generated. Raman resonances are detected by a CARS heterodyne signal generated in a squarehyphen;law photodetector. Theoretical estimations show that a high signalhyphen;tohyphen;noise ratio which is shothyphen;noise limited and effective background suppression are expected with the proposed method independent of the lasers polarization. In typical solvents the sensitivity estimated is khgr;(3)R=4ndash;8times;10minus;18esu, which corresponds to the detection of 1ndash;2times;10minus;4M benzene in cyclohexane.
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