Pump Requirements for Parametric Amplification and Generation of Surface Waves on YZ LiNbO3

Expressions are developed for estimating the threshold electric fields required for parametric amplification or generation of surface waves in piezoelectric materials utilizing the nonlinear characteristics of the material. When applied to YZ LiNbO3, they yield values in excess of 20 kV/cm under the most optimistic, yet still realistic, conditions. These values are too large for amplification or generation to be considered for practical applications. Several pump electrode geometries and circuit matching techniques were investigated to determine the best obtainable pump circuit performance. An interdigital electrode separated from the crystal by a small gap was found to be the most efficient pump electrode geometry and was capable of producing approximately 2kV/cm of field per watt1/2of input pump power.