Enhanced sensitivity of optical fiber vibration sensor based on radio-frequency Michelson interferometer.

We propose and demonstrate a new scheme for enhancing the sensitivity of an optical fiber vibration sensor based on microwave interferometry, which is realized by an incoherent optical Michelson interferometer (MI). The sensing arm of the MI is sensitive to environmental vibration; this will cause changes in the phase of the reflection spectra in the microwave domain. The phase sensitivity can be improved by adjusting the power ratio of the two beams in the interferometer and the driving frequency of the modulator. The system can overcome the problem of interference fading so that it is immune to environmental disturbance. The proposed scheme has merits of simplicity and compact configuration, and may provide a new type of high-precision fiber sensor for measuring vibration, temperature, strain, and so on.