70+ μm deep domain inversion in X-cut LiNbO3 and its use in a high-speed bandpass integrated-optic modulator

A deep domain inversion (DI) technique for X-cut LiNbO3 is reported. DI regions as deep as 70 μm, i.e., deep enough for virtually any guided-wave application, were obtained by electric-field poling, with even deeper DI regions possible. As an application of the DI technique, a bandpass traveling-wave Mach–Zehnder modulator is demonstrated with a 15 GHz bandwidth centered at 21 GHz.