Correlation of Ge E′ defect sites with second-harmonic generation in poled high-water fused silica

Second-harmonic generation (SHG) in poled high-water fused silica was found to be linearly dependent on the relative concentration of Ge E' defect sites (<10(-15) defect sites/cm(3)) for the highly pure UV-grade material. For commercial-grade material characterized by higher concentrations of Ge E' defects sites, the SHG appeared to saturate at approximately 0.5 pm/V. No dependence of the SHG was found on the relative concentration of Ge E' defects sites in poled commercial-grade low-water fused silica.