Research On Integrated Optical Phase Modulator With Y-Branch Profile For Fiber-Optic Gyro

In the area of the inertial sensor the Fiber-Optic Gyroscope(FOG) has been the most competent new leading instrument, and the Interferometric Fiber-Optic Gyroscope(I-FOG) has become ripe and has been in the stage of the engineering development. The design and fabrication of The Y-branch modulator which is the important device of the I-FOG is very significant. So this paper is intended to tell the basic principle of the FOG, the design and manufacture technique of the Y-branch modulator and the test theory and results of the Y-branch. First, this paper has introduced the development situation of FOG and the integrated optics, and discussed the basic theory of FOG, the Sagnac phenomenon. Then the reciprocity of FOG, the bias and modulating technique and the integrated optics FOG is analysed detailedly. Considering the Y-branch modulator when the simulating closed-loop FOG is modulated by the sawtooth wave the unideal performance of the Y-branch would affect the output signal of FOG which results in the generation of multiple sidebands. The major sources of the LiNbO3 device are composed of the unideal electric performance, the additive intensity modulation due to the imaginary modulation of the refractive index, the fiber-waveguide polarization axis misalignment and the backward reflected beam between the fiber and the waveguide. To the design of the Y-branch optic waveguide bending loss, the pure bending loss theory and the finite difference beam propagation method(FD-BPM) are used to analyze two kinds of Y-branch with different S-shaped channel waveguide bends by Matlab and get the optimization of the Y-branch waveguide profile. To design the electrode of the modulator the conformal mapping(CM) technique is introduced to study the width, height and the space between two electrodes, and the optimal parameters of the electrode design are gotten. In the aspects of the fabrication of Y-branch, the theory and experiment of the anneal proton exchange technique and the electrode are introduced, and the technics...