Experimental realization of generalized quasi-periodic structures for multiple nonlinear interactions

Summary form only given. We show a novel method for the simultaneous phase-matching of any two nonlinear interactions, which uses a generalized quasi-periodic modulation of the nonlinear coefficient. This method has now been tested experimentally. We report here multiple-peak frequency doubling in a KTiOPO/sub 4/ quasi periodic structure (QPS), as well as simultaneous second-harmonic generation sum-frequency generation in QPS. These QPS exhibit conversion efficiencies similar to those obtained with cascaded structures. Moreover, they exhibit the same efficiency in both directions of propagation.