The development of masers and lasers has been reviewed in the 1964 Nobel lectures by Townes (1) and by Basov (2) and Prokhorov (3). They have sketched the evolution of the laser from their predecessors, the microwave beam and solid state masers. Lasers are sources of coherent light, characterized by a high degree of monochromaticity, high directionality and high intensity or brightness. To illu...

We give an idea of the evolution of mathematical nonlinear geometric optics from its foundation by Lax in 1957, and present applications in various fields of mathematics and physics.

The invention of the laser provided enough light intensity that nonlinear optics (NLO) could be observed for the first time, almost exactly one year after the first ruby laser – second harmonic generation, observed fifty years ago (Franken, 1961), with a theoretical examination of interactions between light waves in a nonlinear dielectric following very soon thereafter (Armstrong, 1962). The fi...