Laser beam-induced non-linear effects in optically active media

A general equation is proposed for the dynamical electric permittivity tensor, taking into account, besides frequency dispersion, spatial dispersion describing the linear and non-linear optical activities of the medium. It permits one to determine the symmetry relations and value of the optical Kerr effect, a generalised Havelock relation, and the non-linear change in optical rotation angle for arbitrary conditions of observation. Simple examples are adduced to give a microscopic interpretation of the results derived, rendering apparent the basic mechanisms (fluctuations of density, non-linear changes in the optical polarisability tensor and gyration tensor, molecular reorientation, and various radial and angular correlations) leading to induced optical non-linearities. Measurements of non-linear changes in optical rotation angle are shown to be promising in solutions of polymers or colloids, and will permit,inter alia, direct determinations of the anisotropy of gyration properties of molecules macromolecules and colloid particles.A brief summary of the contents is to be found in the Review of the International Quantum Electronics Conference held at Miami on 14–17 May 1968, published inIEEE J. Quantum Electronics,QE-4 (1968) 330.