Design of Double Y Branch Waveguide in Acceleration Seismic Geophone

Dual M-Z interferometer is the sensitive element of three-component acceleration seismic geophone, while Y branch waveguide is the basic optical components composed of dual M-Z interferometer, so the design of Y branch waveguide directly affects the performance of threecomponent acceleration seismic geophone. Firstly, branch waveguide and S-shaped bent waveguide are introduced, and symmetrical double Y branch S-shaped bent waveguide is designed based on this. Secondly, the bending loss of the branch waveguide is analyzed and calculated. The transmission of 1/2Y branch waveguide and 1/4Y branch waveguide , and the bending loss changes with the length of 1/2Y branch waveguide and 1/4Y branch waveguide is simulated by MATLAB. The result shows that the maximum bending loss of 1/2 Y branch waveguide is the 0.156dB, and the bending loss is close to 0 after L>320μm; the maximum bending loss of 1/4 Y branch waveguide is 0.058dB, and the bending loss is close to 0 after L>200μm. The design of double Y branch meets the requirement of low loss. Thirdly, the optical power conversion of branch waveguide in 3dB coupler is simulated and analyzed. Finally, proton exchange and Ti diffusion technique are compared; the advantages of proton exchange technology are summarized; the principle of proton exchange is introduced; and a good proton exchange annealing condition is summarized. Index items—acceleration; photoelastic waveguide; 3dB coupler; dual M-Z interferometer