A graphene oxide-polymethylmethacrylate (GO-PMMA) microfiber sensor is proposed and experimentally demonstrated in this paper, which is based on the absorption principle of near infrared spectra for external refractive index sensing. The sensor was fabricated by splicing a section of 1 mm GO-PMMA between two tapered single mode fibers. The hydrophilic groups of graphene oxide can be used to measure the proportion of water in glycerol solution, and achieve the goal of refractive index measurement indirectly. Experiments were conducted for moisture content of 4.3%~45% (refractive index range from 1.3400 to 1.4054) in glycerin solution. Different concentrations of glycerol solution have different intensities of absorption peaks near 1530 nm wavelength. The absorption peak power near 1530 nm wavelength responses to the external refractive index was experimentally studied. The results show that the sensor possesses a high sensitivity of 167.39 dB/RIU in the refractive index range of 1.34~1.41 and has a good linearity response to external refractive index. The proposed sensor is attractive owing to its high measurement speed, accurate, no pollution and lower cost, and is suited for long-term online real-time measurement.
Up-down Taper Based In-Fiber Mach-Zehnder Interferometer for Liquid Refractive Index Sensing
