This book focuses on characterization techniques that are based on secondorder
nonlinear optical processes. Examples of second-order nonlinear
optical processes include the linear electro-optic (or Pockels) effect and
harmonic generation processes such as second-harmonic generation (SHG)
and sum- and difference-frequency generation (SFG and DFG). The first
effect has been used mainly in applications such as ultra-fast modulators
and switches, whereas harmonic generation processes have been applied
in frequency conversion devices. Furthermore, second-harmonic and
sum-frequency generation received attention because of their potential as
powerful characterization techniques in physical and physico-chemical
labs.