Design on waveguides coupler for integrated fiber optical gyroscope based on SOI wafer

The application of SOI wafer in integrated optical components provides a novel method of increasing the density of integration, as well as reducing unit cost. This paper designed a new kind of waveguides coupler for an integrated optical transceiver unit of an interferometric fiber optic gyroscope system. Based on effective index method and beam propagation method (BPM), mathematic model of the waveguides coupler was founded, and theory calculation and analysis were finished for key parameters, such as coupling ratio, effective coupling length, division radio and returning loss, etc. Also these parameters were optimized in practice coupler design which used in integrated optical transceiver. The design results indicated that its division radio is 50%:50%, coupler core size is 6μm×5.5μm, length of the chip is 25mm and width between two export ports of the waveguides is 400μm. With electron beam lithography machine the mask of silicon-on-insulator (SOI) waveguides coupler was fabricated. The mask fabrication parameters were developed and optimized in this paper. Detect results shown that this optical waveguides coupler can be used in integrated optical transceiver unit for the interferometric fiber optic gyroscope system. This result can provide significant theory basic for research on high integrated, high reliably, low cost integrated optical components used for interferometric fiber optic gyroscope.