Design of quasi-velocity-matched LiTaO3 phase modulator

In common electro-optic modulators (EO), the inherent velocity mismatching between the optical wave and microwave is the major factor hampering efficient modulation. In this paper, we briefly compare periodically reversed electrode and domain reversal scheme (two ways of achieving quasi-velocity- matching), then we give the design principle of the EO modulator using domain reversal scheme. At last, we conclude that the bulk LiTaO3 EO modulator can obtain quasi- velocity-matching at special frequency and make the modulation index increase proportionally to the interaction length. As an experiment, we use a 1.06 micrometer laser as a light source and a modulating microwave source at 6 GHz (16 W). We can expect that we will get at least 3.0 rads of modulation index.