Solution-concentration Sensor Using a Fused Fiber-optic Coupler

In this paper, an optical fiber sensor is reported to be capable of measuring the concentration of the solution. When a 2times2 fused tapering single-mode optical fiber coupler is immersed in the solution, the light propagating through the fused tapered coupler and makes the coupling ratio (CR) sensitive to the variation of the liquids concentration surrounding the fused tapering zone of the coupler. So, the sensor can be realized. As a result, the solution concentration can be measured by the corresponding change of the CR. In addition, the theoretical and experimental processes are presented in the paper.