Enhancement of second-harmonic generation in thermally poled fused silica by multi-energy argon ion implantation

Abstract

The argon (Ar) ions at dose of 1015cm−2 and energy of 10–50 keV are successively implanted in the fused silica glass plate. The total depth of Ar ion doped region is about 140 nm, and the maximum atomic percentage concentration is ~3.9 at.%. The second-harmonic generation (SHG) signal of the thermally poled Ar ion implanted fused silica is in linear relationship to the poling temperature. The SHG signal of the implanted fused silica at high poling temperature is at least 1.6 times higher than that of the unimplanted fused silica under optimum poling conditions. The alkali metal ions (mainly Na+ ions) or H+/H3O+ ions release, point defects/structural modifications, nonstoichiometric layer and compacted structure created by the Ar ion implantation in silica glass or SiO2 oxide layer are believed to be connected with the generation mechanism of second-order optical nonlinearity (SON) in the Ar ion implanted fused silica. The charge migration model of mobile ions can qualitatively explain the relationship between the SHG signal of poled implanted sample and poling temperature.