PRACTICAL SILICON PHOTONIC MULTI-FUNCTION INTEGRATED-OPTIC CHIP FOR FIBER SENSOR APPLICATIONS

This patent disclosure is based on silicon instead of LiNbO3, waveguide chip. The disclosed silicon-based multi-function integrated-optic chip comprises of unique design and fabrication features onto it. First, a unique polarization-diversity coupler is designed and fabricated to couple the external light into the silicon waveguide structure. Then TE mode is guided into a silicon slab waveguide, but TM mode is confined and diverted 90 degree in a silicon carbide structure till the chip edges for TM-mode suppression. Second, a unique two-step (vertical and lateral) taper waveguide region is designed and fabricated to bridge the polarization-diversity coupler output with the input of a multi-mode interferometer (MMI) splitter for power loss reduction. In this configuration, MMI may be a 1×2 or 2×2 structure to divide the input TE mode into a 50/50 splitting ratio output to form a Y-junction. Third, at either end of the Y-junction output, there is a phase modulator to achieve optical phase modulation through various physics mechanisms such as plasma dispersion, electro-optics, thermo-optics, or photo-elastic effect. With this newly-developed silicon-based multi-function integrated optic chip, the size and cost of fiber sensors including FOG's can be greatly reduced.