Pressure and power dependence of the optically heterodyne Raman-induced Kerr effect line shape

The effect of pressure and laser power on the high-resolution spectra of commonly available gases is studied with the help of the optically heterodyne Raman-induced Kerr effect (OHD-RIKE). The results show the expected pressure dependence of the spectra, but the effects of saturating laser power are different from previous similar studies employing other four-wave mixing techniques. In OHD-RIKE no observable sign of saturation such as power broadening, saturation dips in the line center, or deviation from a linear dependence of the signal strength with laser intensity was observed for several orders of magnitude greater intensities than previously reported for the saturation intensities in coherent anti-Stokes Raman spectroscopy (CARS). Saturation is therefore not the ultimate limit of sensitivity for OHD-RIKE. This may be an advantage of RIKE in comparison to other coherent Raman techniques.