Dielectric characteristics of silica glasses and their relationship to SHGin poled silica

Electrical and dielectric relaxation measurements were conducted in silica glasses. Using the results of the measurements the cause of second harmonic generation (SHG) in thermally, poled silica glass was considered. Absorpti on currents were measured as a function of time for various types of silica glasses and analysed using the theory of space charge polarisation. It was found that generation, annihilation, reproduction and temperature dependen ce of SHG in poled silica are similar to those of space charge polarisation . The fundamental parameters governing SHG in poled silica were found to be charge carrier concentration and mobility. Based on the theory of space ch arge polarisation, and the experimental result of electrical relaxation, a method to increase the intensity, of SHG is proposed.