On the role of permanent dipoles in second harmonic generation

D L Andrews, W J Meath
1993 Journal of Physics B: Atomic, Molecular and Optical Physics  
The significance of permanent electric dipoles in second harmonic generation is considered with regard to their role in both the non-linear susceptibility and also in the orientation of polar molecules. Under conditions of near-resonance with the first electronic excited state, the susceptibility is dominated by a two-level term governed by the difference between the ground-and excited-state dipoles; this term alsa drives the harmonic conversion in electric field-induced second harmonic
more » ... on. It is shown that ifthe resonant level is not the lowestelectronic excited state, there is a secondary resonance feature which can contribute just as stmngly JS the two-level term. and which can dominate the harmonic conversion if the ground-and excited-state dipoles are either equal, or both zero.
doi:10.1088/0953-4075/26/23/030 fatcat:2qbf7e7xdfdaljnq3x3h7wwqga