Analysis of phase matching conditions for generating second harmonic in ZnO channel waveguides

We describe a phase-matching scheme for generating the second harmonic in ZnO channel waveguides using a modal phase-matching (MPM) method. We found that MPM can be achieved between the TM ₀₀ mode of the fundamental wave and the TM ₀₂ mode of the second-harmonic wave by using structural dispersion of the waveguide mode. Furthermore, we calculated the normalized conversion efficiency by taking the overlap integral of each waveguide mode and the effective area of the fundamental wave into account, and obtained a sufficiently high conversion efficiency. These results show that ZnO channel waveguides are very attractive for generating second-harmonic devices.