The nonlinear optical effects described in Chaps. 4 and 5 have to be characterized for a given material up to a certain level before they can be applied in photonics. The already wide range of applications in science, technology and medicine contains analytic aspects, questions of the structure of matter, reaction mechanisms on all time scales and the production of new states, phases or even of new matter. Thus two main questions are asked in nonlinear optics: Which nonlinear optical effect is, for a given material suitable for a new laser analytic method (analytic tasks)? Which nonlinear optical effect is most suitable for a desired photonic application (material and light modification tasks)?