Paper 1.8: N. Bloembergen, “Nonlinear optics; a historical perspective,” in Huyghens' Principle, edited by H. Block, H.A. Ferwerda and H.K. Kuiken, Elsevier Science Publishers, 1992, pp. 383–394.

This paper was originally presented at a conference held in Scheveningen, the seaside resort near The Hague in the Netherlands in the fall of 1990. It was a celebration of the 300th anniversary of Huyghens' treatise, Traité de Lumière, which was published in Paris in 1690. In a preface, Huyghens mentioned that he had presented most of the material contained in this book more than a decade earlier in a series of lectures before the Académie des Sciences in Paris. This was to establish his claim to priority, which was just as important then as it is now. His contenders were small in number, but included Descartes and Newton. The dual wave-particle character of light was already a burning issue in that period.

In the past five years I have given numerous colloquia and keynote talks with the same title as this paper and the topic is apparently of general interest. Since the book in which this paper was first published is not well known in the quantum electronics community, a reprint is included in this volume.

The paper traces the origin of electric and magnetic nonlinearities back to the nineteenth century. It does not include a reference to the quadratic Kerr effect, “A new relation between electricity and light; Dielectrified media birefringence,” John Kerr, Philosophical Magazine and Journal of Science (fourth series) 50, 332–348, 1875. I originally omitted this reference because, unlike the Pockels effect, the Kerr effect is not a pure electronic nonlinearity. Kerr mentioned explicitly in his papers the long times it takes for material electric dipoles to align themselves in glass, and that the times for molecular reorientation in fluids are still much longer than an optical period. This effect could not be extrapolated to third harmonic generation, or to other third-order nonlinearities involving arbitrary optical frequencies. Nevertheless, a discussion of the Kerr effect and a reference to it is appropriate in the historical context.