Multi-parameter sensor using fiber in-line MZ interferometer embedded in fiber Bragg grating

We propose an ultra compact optical fiber sensor integrating a Mach-Zehnder interferometer (MZI) in fiber Bragg grating (FBG) for simultaneous refractive index (RI) and temperature measurement. By use of the resonant wavelength of the FBG and the interference dip of the MZI, the RI and temperature of the surrounding medium can be unambiguously determined. The interesting properties of the sensor include good operation linearity, extremely high RI sensitivity up to ~9148 nm/RIU (RI unit) in the RI range between 1.30 and 1.325 and precise sensing location, determined by the MZI cavity created.