Determination of the nonlinear fifth-order susceptibility of InSb at the wavelength of 10.6 µ

A direct experimental confirmation was obtained that, because of a two-photon resonance in InSb subjected to illumination at 10.6 µ wavelength, the main contribution to the reflection in the case of a four-wave interaction came from the nonlinear fifth-order susceptibility χ⁽⁵⁾. The absolute value of this susceptibility was found to be χ⁽⁵⁾≈8×10^–8 cgs esu for InSb and ways of increasing it by 1.5–2 orders of magnitude were considered.