Ii. Microwave Spectroscopy Academic and Research Staff

It is fairly evident that one should be able to observe nonlinear effects in the interaction of lasers with matter. A 1-MW laser can create an electric field a few volts per angstrom in matter. Since this is on the order of atomic fields, it is not surprising that nonlinear interactions are observable in matter not possessing a center-of-inversion symmetry. In contrast, it is certainly not evident that nonlinear effects can be observed from the interaction between matter and microwave sources of a few watts. Resonance between the field frequency and the energy levels of the matter, however, enhances the nonlinear effects by many orders of magnitude. Furthermore, if a static magnetic or electric field is applied, centro-symmetric matter such as a gas can give rise to observable nonlinear interaction. Since microwave wavelengths are of the order of the sample size, the problem of phase matching, which can be a limitation in the observable laser nonlinear effect, is easily dealt with.