ABSTRACT
The classical treatment of propagation, light superposition, reflection,
refraction, etc. assumes that there is a linear relationship between the
electromagnetic field and the responding atomic system comprizing the
medium. We know that an oscillatory mechanical device such as a
weighted spring can be driven into a non-linear response with the
application of large enough forces. In the same manner an intense light
beam, such as a laser beam, can generate appreciable non-linear optical
effects. The realm of non-linear optics encompasses these effects, in
which high-intensity electric and magnetic fields play a dominant role.
