Error analysis of electric field sensor caused by laser wavelength shift

Electro-optic integrated electric field sensors based on the Pockels effect are widely used. This study analyzed the measurement error caused by the laser wavelength shift and the underlying theory that explains it. Numerical methods were used to obtain the distribution of the modulated electric field, the fundamental mode optical field and the refractive index of the LiNbO3(LN) crystal after titanium was diffused in the cross section. The results show that the increase of the wavelength keeps the maximum intensity of the optical field centre away from the waveguide surface, moving it to the low electric field intensity region and reducing the electro-optical overlap integral factor. The relationship between the relative error of the measured electric field and the wavelength shift was finally determined through calculation.