Abstract
We draw attention (theory and experiment) to the interference wedge (IW)1-3 property to present a strong asymmetry in reflection, when it is built of non-equal reflectivity mirrors and we show how this failure permits to develop attractive unidirectional ring lasers. In proposed ring cavity schemes a single IW is used simultaneously as a tuning element, as an element introducing asymmetry and as a laser output coupler. This is an advantage in comparison with the conventional schemes with Faraday rotator4 or a reinjecting extracavity mirror.5