Applications of High Power Lasers

At high intensities electromagnetic waves behave strongly nonlinear, at a degree which goes far beyond the familiar nonlinear optics. The origin of the drastically increased nonlinearity has two kinetic roots. The first is the Lorentz force. The \({\mathbf {v}}\times \mathbf {B}\) term generates, at moderate laser strength, electron motion of \(2\omega \) and also zero frequency motion. The other root is the convective term \(({\mathbf {v}}\nabla ) {\mathbf {v}}\) which acts similarly, but with different strength in general. With increasing field intensity higher harmonics of the laser frequency govern more and more the current densities and “contaminate” the \(\mathbf {E}\) and \(\mathbf {B}\) fields through the Maxwell equations. These, in turn, act back onto the current densities to generate the world of nonlinearities. A third root of nonlinearities stems from the distortion of the fields of atoms and ions by the incident laser field itself.