▎ 摘　　要

We report on moisture detection in transformer oil based on an optical waveguide fabricated using graphene oxide (GO). The SU-8 polymer channel waveguide was coated by GO film, using a drop-casting technique. Here, for the polarized light, high absorption of transverse electric (TE) was achieved for the proposed sensor at wavelength 1550 nm. Changes in TE-polarized light absorption by the device were measured at varying water contents. Experiments were carried out for water contents in oil in the range of 16-21 ppm as well as immiscible (free) water in oil. Our observations showed a difference in the results trend obtained for different relative water contents. The TE-transmission power increased linearly with higher water content in transformer oil. A power change of +0.90 dB/ppm of water content in transformer oil was measured within the range tested. A simulation analysis using the finite element method FEM was also carried out. The proposed sensing mechanism can be used under these sensing conditions. This approach also has a fast response time as well as high sensitivity.