Electrooptical Modulator Fabricated by Gallium Diffusion in Lithium Niobate

Mach-Zehnder modulators fabricated by gallium diffusion in y-cut lithium niobate (LiNbO) are presented. The measured halfwave voltages are 6.2 and 3.2 V when the electrode lengths are 0.4 and 0.8 cm, respectively. By calculating the overlap integral between the modulating electric and the guided optical fields, the value of the electrooptic coefficient is found in good agreement with that of the bulk LiNbO, which indicates no significant degradation in is induced by the in-diffused gallium atoms.