Abstract
The mutual interaction of counterpropagating waves in a ring resonator containing a medium with second-order dispersive nonlinearity is studied. The theoretical treatment of nonreciprocal propagation is based upon the novel coupling of counterpropagating and mode-locked first- and second-harmonic waves. The experimentally observed transfer characteristics of a high-frequency model system reveal a directionally asymmetric bistability. This nonreciprocity can also be attributed in the time domain to the occurrence of dissipative structures, i.e., to solitons traveling within the resonator.