Optical Current Sensors Consisting of Polymeric Waveguide Components

Optical current sensors are demonstrated based on polarization rotated reflection interferometry by incorporating polymeric optical waveguide components. Polarization maintaining 3-dB couplers, TE-pass waveguide polarizers, and thermo-optic phase modulators are designed and fabricated in this work in order to provide essential building blocks for constructing the current sensors. The phase difference between the two circularly polarized waves imposed by the Faraday effect of the optical fiber is detected using the interferometric optical sensor consisting of the polymeric components. To remove the bending induced birefringence, the optical fiber wound around a ceramic frame is annealed at 850°C for 24 hours. The reflection interferometer comprising the polymer waveguide components operates with good linearity proportional to the monitoring current.