Quasi-phase-matched optical parametric oscillation with periodically poled stoichiometric LiTaO₃

We have demonstrated, for the first time to our knowledge, periodic poling of a 2-mm-thick near-stoichiometric LiTaO₃ substrate and its operation in a nanosecond optical parametric oscillator. Because the coercive field of stoichiometric LiTaO₃ is ∼2 kV/mm, which is approximately one tenth that of the conventional congruent field, periodic poling of thicker stoichiometric substrates was successfully performed by means of an electric-field poling process at room temperature. The performance of a parametric oscillator with a 1-mm-thick sample was compared with that of the oscillator with the periodically poled congruent oscillator. The stoichiometric device exhibited better performance.