Absolute determination of the two-photon-absorption coefficient relative to the inverse Raman cross section

A new method for the direct measurement of two-photon-absorption (TPA) coefficients relative to known inverse Raman cross sections is reported. The method is independent of the laser-beam parameters utilized in the experiment. The TPA cross section of Ti${\mathrm{O}}_2$, GaP, CdS, and SrTi${\mathrm{O}}_3$ due to simultaneous absorption of a photon at 14403 ${\mathrm{cm}}^{-1\mathrm{}}$ and a photon at 17248 ${\mathrm{cm}}^{-1\mathrm{}}$ was determined relative to the cross section of the 2855 ${\mathrm{cm}}^{-1\mathrm{}}$ Raman mode of liquid cyclohexane. Accurate Raman cross sections may also be measured by the proposed method.