Letters

It was a great pleasure to read Jeff Hecht's interesting historical article, "How the Laser Launched Nonlinear Optics" (OPN Nov. 2010). It recalled for me my early attempts to understand and organize the field of nonlinear optics as a young researcher by "deciphering" its basics and tracking its history. I did this in Romania during the late 1960s, and my efforts resulted in the first Romanian book on nonlinear optics (Introduction to Nonlinear Optics, Romanian Academy Publishers, Bucharest).