Reflected second-harmonic generation at a silver surface

Abstract

Quantitative measurements of reflected optical second-harmonic generation (SHG) versus the angle of polarization of the incidence from the interfaces between opaqe silver film and several glasses are presented. Measurements of the reflected SHG from the surface of a vacuum cold-evaporated thick silver film on a polycrystalline silver substrate in an ultrahigh-vacuum (UHV) chamber before and after annealing the specimen are also given. For comparison, the reflected SHG from a 99.99% pure and finely polished polycrystalline silver surface was detected in UHV. By calibrating the reflected s- and p-polarized SHG from the silver film to the transmitted SHG from a z-cut quartz crystal, the values of tengential- and normal-current parameters a and b could be determined. The measured value of the phenomenological parallel-current parameter b is equal to -0.97 for the glass-silver interface. And the normal-current parameter a has a value of 2.1 for the glass-silver interface and -9 for the polycrystalline silver surface. The value of a varies with the sample annealed from 7 to -5 for the cold-evaporated silver film on a polycrystalline silver substrate. The experimental results show that the SHG signal is sensitive to the structure of the silver film. Electrodynamic theory is used to fit the experimental results.