Simultaneous measurement of temperature and refractive index based on a Mach-Zehnder interferometer cascaded with a fiber Bragg grating

An all-fiber sensor for simultaneous measurement of temperature and refractive index (RI) is proposed and demonstrated. The sensor head is composed of a Mach-Zehnder interferometer (MZI) and a fiber Bragg grating (FBG). The MZI consists of a peanut-shape structure and a core-offset structure which are formed only by single mode fibers through different fusion technology. Experimental results show that the temperature sensitivities of the FBG (dip1) and the MZI (dip2) are 0.01228 nm/°C and 0.08329 nm/°C, respectively. Dip1 is insensitive to environmental RI, but dip2 is sensitive to environmental RI, and the sensitivity is −26.965 nm/RIU. Therefore the simultaneous measurement of the temperature and RI is demonstrated based on the sensitive matrix. The novel sensor processes low fabrication cost, simple configuration, high sensitivity etc. It will have attractive potential applications in chemical and biological sensing fields.