Hybrid Mach-Zehnder interferometer manufactured by femtosecond laser multiscan technique

In this paper, a 6 mm hybrid Mach-Zehnder Interferometer (MZI) has been manufactured within a standard optical fiber using multiscan inscription with femtosecond laser. This technique allows the employ of cladding waveguides (CWG) as sensing arms for the interferometer. Refracted Near Field (RNF) profilometry and Quantitative Phase Microscopy (QPM) consistently suggest that CWG exhibit a smooth Type I refractive index change (RIC) that increases with the number of scans. This makes the scan number a potential way to control the coupling and Free Spectral Range (FSR) of the manufactured MZI. Its combination with a fiber Bragg grating (FBG) inscribed in the core makes possible to discriminate between different parameters.This work has been supported by the project TEC2016-76021-C2-2-R (AEI/FEDER) of the Spanish government and FEDER funds