Report on second harmonic generation in soda-lime glass and relative new phenomena

We report the second-harmonic generation in soda-lime glass for the first time. During poling some white material coated on the glass surface on cathode side. By ESCA analysis the white material is mainly a compound of sodium, which is the first evidence to prove the supposition that sodium captions move towards the cathode in the glass during the poling. This may help us to understand the mechanism of second-harmonic generation in the poled glass. We found the signal of second harmonics decreases with time after poling and the damping rate depends on the surrounding temperature. The signal decay in fact is the decay of the electric field and the charged particle inside glass. There is a residual signal after damping for one week, which does not change for months. The residual signal depends on the poling temperature. Thus we have to assume that there are two kinds of negative particles in the poling process in soda-lime glass.