Quantum optics has become a key field of development for investigations of quantum physics principles, leading to novel quantum technologies. In this view Integrated Optics allows implementing complex quantum circuits that can give rise to significant outcomes, difficult to reach using traditional approaches based on discrete components. In this framework, a non-linear Mach-Zehnder Interferometer (MZI) was implemented by using two commercial 50:50 directional fibre couplers. One of the MZI arms was equipped with a single mode Er:LiNbO3 optical waveguide, acting as non-linear component whereas the other MZI arm was provided with an undoped LiNbO3 single mode optical waveguide, used to obtain a phase shift through the application of a controlled voltage ramp. The injection in the MZI of a 980nm wavelength laser radiation allowed to collect structured interferogrammes, that could be ascribed exclusively to the pump photons, as all frequency conversion events are localized only in one arm of the Interferometer. The Fourier Transform elaboration of such interferogrammes, produces multiple peak spectra that tightly match the typical transition spectrograms of Er:LiNbO3 when excited by a 980nm radiation. Thus it is possible to perform a spectrometry of the noninterfering converted photons only by using the interfering pump photons. In this work, the experimental apparatus and the most interesting results, obtained in different experimental conditions, are described. Finally, a possible interpretation is outlined.