A new optical fiber micro-bend pressure sensor using fiber loop ringdown is studied in this paper. It consists of a pulse microchip laser, two 2*loptical fiber couplers, a photodetector, and a section of fused-silica single-mode fiber, which makes the sensing element with a micro-bend structure. Pressure can be measured by measuring the ringdown time of fiber loop due to the monotone relation of fiber transmission loss and the micro-bend of the single mode fiber. A test setup is constructured, then the ringdown time corresponding to different pressure, which is simulated by putting different heavy masses on the micro-bend panel. The experimental results show that the pressure has good linear relation with the reciprocal of the ringdown time, which is well in agreement with the theoretical results. This new fiber sensor is free from the fluctuation of the light power, which badly affects the performances of traditional fiber micro-bend sensors. Furthermore, it has the advantages of simple structure, fast response, highly sensitivity, convenience for multi-parameter sensing, etc., which makes it have wide applications.
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