Second harmonic generation in coupled LiNbO/sub 3/ waveguides

Summary form only given. It is known that as proton-exchanged (PE) lithium niobate (LN) undergoes the reverse process (RPE), a partial restoring of lithium-ion content occurs. In z-cut LN substrates, the above phenomenon defines a surface waveguide for TE polarization, and a buried one for TM polarization. Here, we present SHG experiments in unpoled, 17 mm long PE-RPE planar waveguides in z-cut LN.