The Enhancement of Second Harmonic Generation Modulated by the Field of Fundamental Wave

The second harmonic generation (SHG) from one-dimensional periodic optical superlattice embedded into air is studied. It is found that the SHG conversion efficiency can be modulated by the field of fundamental wave (FW). In order to investigate the effect of the FW on the SHG, nonlinear non-polarized material is added in back of a crystal and the corresponding SHG conversion efficiency is calculated. Results show that the SHG conversion efficiency can be enhanced significantly when transmission resonance takes place, however, for different resonant peaks the values are different. In addition, the SHG conversion efficiencies can be modulated about 5 times by adjusting the thickness of added material.