Characterization of Femtosecond Laser Direct Written Mach-Zehnder Interferometers Based on Titanium Dioxide Coated Long Period Fiber Gratings

Optical fiber Mach-Zehnder interferometers were fabricated by combining two TiO2 coated LPFGs fabricated through femtosecond laser direct writing. Results of its refractometric characterization are presented and compared with the single LPFGs sensors. Wavelength sensitivity of 1175 nm/RIU at 1.38 and spectral resolution of 2.2x10-5 were achieved.