Using (As Opposed To Studying) X/sup (3)/

The ultimate goal of science is to use knowledge to mampu1ate nature. In nonlinear optics, the phenomenon of nature we wish to manipulate is light. The second order nonlinear susceptibility - ϰ ϰ
^<2)
- has shown great promise in this regard. The situation with the third order nonlinear susceptibility is more problematical. In 1990, technology can provide field strengths sufficient to make processes of any order as strong as those of lowest order. Why is it then that the third order nonlinear susceptibility remains largely a laboratory curiosity?