Tightly confined, low-loss waveguides in highly nonlinear materials permit nonlinear optical interactions to occur over much shorter distances than do fibers. The nonlinear interactions are further enhanced in resonators. Both theory and experiment of enhanced four-wave mixing in micro-ring resonators are presented that can be used for many applications. A conversion efficiency of 14% achievable with only 10-mW peak pump power is predicted under realizable conditions. The experiment, the first one to the authors' knowledge in nonlinear optics performed in micro-rings, shows, even in a lossy GaAs/AlGaAs ring, a 26-dB improvement in the conversion efficiency compared with that of an equivalent straight waveguide, in agreement with theory. (C) 2000 Optical Society of America. OCIS codes: 130.3120, 130.4310, 230.5750, 230.4320, 190.2620.
