Abstract: An asymmetric feedback structure in a ring laser produces essentially unidirectional lasing. The structure can be dynamic to permit directional control, or can be passive to provide unidirectional lasing in a predetermined direction. Dynamic control is obtained by a dielectric stack in the laser cavity, the stack including multiple layers having complex impedances for reflecting incident light. The amount and direction of reflection is controlled by varying the refractive indices or the absorption coefficients of the materials in the layers to produce cross-coupling for one direction which is different from the other direction. Passive control is obtained by introducing an asymmetry into the propagation path of the laser. This may be in the form of an optical diode structure or a tapered waveguide structure to produce asymmetric cross-coupling of counter-propagating modes of the laser light.