OPEAK's Multi-integrated optical circuit (MIOC) is a LiNbO 3 based Integrated Optical Circuit incorporating a polarizing waveguide, phase modulators, a power splitter/mixer and polarization maintaining fiber pigtails. Using Annealed proton exchange (APE) technique, it passes only the transverse electric component so as to show high extinction ratio. The end faces of the device are angled to reduce the back reflection. The input and output pigtail are all polarization maintaining optical fibers (PANDA or others on request) in order to conveniently couple with the coil fiber and reduce the cross talk induce by splicing. The push-pull electrode structure needs very low half-wave voltage. Meanwhile it has excellent environmental stability. So it ‘s very suitable for fiber optical gyroscope and current sensor.