Modulation Asymmetry Suppression of Multifunction Integrated Optic Circuit by Sinking Electrode

Abstract

The modulation asymmetry of a multifunction integrated optic circuit (MIOC) indicates the difference in the phase response to modulation electric fields with the same magnitude but different directions, and is partly caused by the vertical component of the modulation signal. This introduces a nonlinear phase error that is difficult to compensate in fiber optic gyroscopes (FOGs), which needs to be suppressed. In this paper, a sinking-electrode MIOC design to suppress the modulation asymmetry is proposed and verified through numerical simulations. Optimal parameters of the gap, height, side-wall angle, and center position error of the sinking electrodes are obtained on the basis of the simulation results. With the proposed method, the modulation asymmetry of MIOC can be reduced from 5 × 10 −4 rad to 1 × 10 −6 rad, thus facilitating the development of high-performance FOGs. Furthermore, compared with the traditional electrode design, the sinking-electrode design can increase the tolerance for the manufacturing process, and the design configuration can be obtained through the general process method.INDEX TERMS Multifunction integrated optic circuit (MIOC), phase modulator, modulation asymmetry, electrode design.