Integrated Mach-Zehnder micro-interferometer for gas trace remote sensing

The realisation process and the preliminary tests on the performances of an integrated Mach-Zehnder Interferometer on LiNbO3 (Lithium Niobate) substrate is presented. The microsystem has been obtained by using medium mass Ion Implantation on X-cut Lithium Niobate crystals. The interferometer is formed by integrated optical channel waveguides; the phase shift between the two optical paths has been obtained, without moving parts. by applying a suitable electric field. The whole device is 60mm long, has a O.5xlmm2 cross section and weights a few grams. The power consumption is in the milliwatt range. In the present work results obtained in the spectral window (O.4jim-l .Iim) will be presented. The performance of the device, evaluated on standard radiation sources, demonstrates that a spectral resolution better than O.3nm can be obtained on 400nm spectral windows. The Micro-interferometer has been tested in laboratory with a calibrated cell containing NO2 gas and has demonstrated sensitivity in the ppb range if suitable optical paths are used. Its reduced dimensions and weights make these micro-systems ideal for a wide range of applications, spanning from Space Technology, Earth observation for Environmentmonitoring, to Safety and Security applications.