Generalized Mach–Zehnder interferometers for sensing applications

A sensing application of integrated optical (IO) generalized Mach–Zehnder interferometers (GMZIs) is proposed. GMZIs are multiple-arms Mach–Zehnder interferometers (MZIs) and are widely used in optical telecommunications for wavelength-division multiplexing (WDM) and optical switching. In this paper, we show that GMZIs can be used in order to realize highly sensitive IO refractometers that can be usefully employed in chemical and biochemical sensing applications. These devices, with a suitable design, permit sensitive operation over a wide range of indices without the ambiguities of conventional MZIs. Furthermore, in some applications a direct digital readout is possible.