 Mach @-@ Zehnder interferometers are being used in integrated optical circuits , in which light interferes between two branches of a waveguide that are externally modulated to vary their relative phase . A slight tilt of one of the beam splitters will result in a path difference and a change in the interference pattern . Mach @-@ Zehnder interferometers are the basis of a wide variety of devices , from RF modulators to sensors to optical switches . 
