BACKWARD OPTICAL PARAMETRIC OSCILLATORS AND AMPLIFIERS

Degenerate backward optical parametric oscillators and amplifiers have been considered, for the first time, to the best of our knowledge, Wh en the pump intensity is four times the threshold pump intensity, the conversion efficiency reaches a maximum value, On the other hand, for nondegenerate optical parametric oscillators, the conversion efficienc y always increases as the pump intensity increases. This behavior is d ifferent from those for forward optical parametric oscillators, In eit her configuration, the oscillation can occur without an external feedb ack, There is, however, a distributed feedback provided through the op posite propagation directions of the signal and idler, The threshold p ump intensities for the oscillators can be achieved by the lasers curr ently available based on quasi-phase matching in several structures. A s the input intensity for the backward parametric wave increases, the gain for this wave decreases dramatically if the pump intensity is on the order of the threshold or higher, When the input intensity is much larger than the threshold pump intensity, there is almost no gain reg ardless of the level of the pump intensity.