Modeling and experimental electro-optic response of dielectric lithium niobate waveguides used as electric field sensors

In this paper, the static optical transfer function of dielectric lithium niobate (LiNbO3) electro-optic sensors is modeled and experimentally measured. This function represents the transmitted optical power at the output of an optical waveguide in a LiNbO3 crystal which acts as an electric field sensor. The sensor is electrode-less and operates as a dielectric probe. Under such a condition, the electric field is present in the dielectric media surrounding the waveguide and the measured field intensity is determined by the boundary condition between the media and the LiNbO3 crystal. The electro-optic transfer function is theoretically modeled and experimentally measured. Such a transfer function shows a sinusoidal shape, from which the half-wave electric field, the optical extinction ratio and the linear and nonlinear regions can be determined. LiNbO3 electric field sensors are inherently wide band, and a sensing scheme is tested, showing a high-linearity sensing detection of high-intensity and wide-band electric fields.