Interactions between Light Waves in a Nonlinear Dielectric.

In " THE PHYSICAL REVIEW ", second Series, September 15, 1962. Vol. 127, n. 6, pp.1918-1939, the entire issue in original printed wrappers. A good copy, ownership inscription, wear to spine. FIRST EDITION. The Birth of Nonlinear Optics.
Light’s electric field can polarize the atoms in a material. For low light intensity this polarization is linearly proportional to the electric field. But at high intensities (electric fields ~ 108 volts per meter) the linear dependency doesn’t hold, and new phenomena are observed, such as a change in the light’s frequency as it travels through the material. In 1961, Peter Franken and colleagues ( Phys. Rev. Lett. 7, 118 – Published 15 August 1961) used a high-intensity ruby laser to induce nonlinear behavior in a quartz crystal. They showed that light emitted from the crystal had double the frequency of the incident beam. An in-depth quantum-mechanical treatment of the phenomena was later carried out by John Armstrong and colleagues, providing the theoretical foundations for nonlinear optics. A number of applications in the medical and biological sciences rely on nonlinear behavior, including endoscopy and tissue imaging. ( https://journals.aps.org/international-year-of-light ).