Surface Second Harmonic and Sum‐Frequency Generation

Abstract The use of optical second harmonic generation (SHG) measurement of the exploration of dielectric polarization and related surface phenomena is described. Paying attention to the specific nature of material systems on the surface, orientational order parameters are introduced to characterize surface layers, and the SHG enhancement is described in terms of the order parameters. Also the sum‐frequency generation (SFG) and electric‐field‐induced SHG(EFISHG) are described as a tool of probing carrier motions in surface layers. The experimental system is shown with some results.