ABSTRACT
Second-order nonlinear effects leading to optical frequency conversion was first demonstrated in 1961 by Franken et al. [5] shortly after the demonstration of the first working laser by Mainman in 1960 [49]. Many applications of second-order nonlinear effects have proven successful in various fields; for example as phase or amplitude modulators e.g. in optical communication systems, or to generate almost arbitrary wavelengths from existing laser systems.
