ABSTRACT
Conventional linear and nonlinear optics relate to the interaction between optical radiation and electrons which are bound to a parent atom or molecule. However, as the intensity of a laser is increased, the target atoms or molecules are ionized and the laser radiation then interacts with a highly ionized medium or plasma. The electrons are relatively free to move in the background sea of ions and, as a result, the ionized material has very different optical properties from those of the neutral medium. In addition, the electrons in the plasma can be heated to high temperatures by the intense laser radiation and, at very high intensities, the properties of the plasma are essentially controlled by the laser field rather than the electrostatic fields of the ions and electrons. Thus, the optical radiation can influence such fundamental plasma properties as the density and temperature. Under these circumstances, the interactions involve a highly complex set of physical processes which, in turn, create the possibility of a very diverse range of physical phenomena and applications.
