Application of second-harmonic generation combined with the electro-optic effect for electrical field measurements

Summary form only given. A novel approach of measuring the electric field is proposed by combining second-harmonic generation (SHG) with the electro-optic effect. In SHG with an electro-optic crystal, when the interacting pump and the SHG wave satisfies the phase matching condition, the SHG output can be obtained. However, when an external electric field is applied, the refractive indices alter due to the electro-optic effect and the phase matched condition changes resulting in the output variation which can be used for the measurement of the electric field. The advantages compared with the Pockels sensors are: (1) direct measurement of the SHG output results in higher signal to noise ratio; (2) phase matching conditions can easily be offset to monitor higher electric fields; (3) compact fiber coupled assemblies without waveplates, analyzers are possible. In the present work, a diode laser is used with a nonlinear, electro-optic crystal and the feasibility of SHG for the electric field measurement is studied. The experimental measurements combined with theoretical estimates show that even though the temperature control is a critical requirement, SHG with electro-optic crystals, such as either LiNbO/sub 3/ or KTP, can be effectively used for electrical field measurements.