Polymeric integrated optic current sensors based on polarization rotated reflection interferometry

The real-time power information from the power plants and substations are required for smart grid infrastructure. However, the conventional current sensors are vulnerable to external electromagnetic interference (EMI) and surge current. Therefore, optical current sensors have received high attention for their advantages over the conventional system. Optical current sensors have various merits of insulating sensor materials, linear response over wide current range, and light weight for easy installment. Furthermore, they can be produced in small footprints and are immune to the external EMI, and they can be used in high power capacity. The only disadvantage of optical current sensor is the complicated interferometry structure, which could be resolved by adopting integrated optics. In this work, we designed and fabricated a polymeric integrated-optic device for producing the polarization rotated reflection interferometry (PRRI). By adopting integrated optics, the PRRI could be fabricated by a simple process and is advantageous for mass production. The polymeric waveguide device consists of phase modulators, TE-pass polarizers, directional couplers, and polarization converters integrated on a single chip. It was fabricated through a conventional semiconductor fabrication process, such as photolithography, spin-coating, UV-curing, etc. Finally, the fabricated polymeric integrated optic current sensor exhibited excellent linearity, fast response time, and high accuracy satisfying the 0.2 accuracy class (IEC 60044-8).