A multifunctional photonic integrated circuit (PIC) suitable for the manufacture of fiber optic gyroscopes (FOG) is described. The PIC is constructed and arranged to exhibit a scale factor of substantially high stability and accuracy. The PIC may comprise, for example, a high optical birefringence and low propagation loss waveguide, a low wavelength-dependent split-ratio Y-junction, a high extinction ratio linear polarizer, and high efficiency fiber-to-waveguide mode-size converters. Considerations for ensuring high-level FOG performance are addressed by, for example, optimization of waveguide structure, functional requirements for individual components, and combined effects of the circuit layout. A high-end, tactical grade FOG may be built using the disclosed PIC, after connecting to polarization maintaining optical fiber coil, a light source, and a photodetector.