Comparing the Efficiency of Generating the Second Harmonic in Aluminum and Germanium Silicate Glasses upon Volumetric Optical Poling

The generation of the second harmonic is investigated on microperiodic nonlinear polarizability gratings photointegrated upon volumetric optical poling in aluminum and germanium silicate glasses. A comparison shows the strong impact of nitrogen, phosphorus, and rare-earth element additions. An original theory of nonlinear-frequency conversion using the current mechanism allows the characteristics and magnitudes of photointegrated nonlinearities in glasses to be estimated. A strong dependence is revealed of the efficiency of harmonic generation on the intensity of the poling radiation component, due to the possible influence of photoconductivity. This dependence must be considered when developing promising samples with photointegrated gratings.