Threshold and operation conditions of the interconnected photorefractive ring oscillators are investigated, using the grating action method. Three types of two connected oscillators are considered, the first one consisting of two transmission grating crystals, the second one of two reflection grating crystals, and the third one of one transmission and one reflection grating crystal. It is found that, under similar conditions, the transmission-transmission ring possesses the lowest threshold and attains the highest reflectivity of the three.
