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Advances in two-mode optical fiber sensors incorporating photoinduced refractive index gratings

The effects of such parameters as exposure time, exposure power, and elevated temperature exposure on the growth and performance of photoinduced two-mode gratings are presented. We also present the results of an investigation into the possibility of utilizing the two polarization axes of an elliptical-core two-mode fiber to monitor two vibration modes simultaneously with one optical fiber. Two separate gratings are written onto a separate axis of a single two-mode fiber. Each polarization will be used to monitor a different vibration mode of a thin cantilever beam. The effects of the formation of a second grating on the performance of the first grating are investigated, and results are presented. These results will determine the feasibility of using the two polarization axes to monitor two vibrational modes of a structure.