Ti-LiNbO3 Waveguide Serrodyne Modulator With Ultrahigh Sideband-Suppression for Fiber Optic Gyroscope

Serrodyne modulation using an electro-optic (E-O) phase modulator in a Ti-indiffused LiNbO3 waveguide for optical frequency shifting is being developed for a variety of app1ications.1 Sideband suppression better than 40 dB at a moderate shifting frequency (40 KHz) has been reported.2 Inertial navigation, phase-nulling rotation sensors utilizing Sagnac interferometers, however, require extremely high sideband suppression and shifting frequencies of up to several hundred kilohertz in order to achieve scale factor linearity over a wide dynamic range.3-4 In this paper, we report a serrodyne modulator with an overall sideband suppression of better than 50 dB at frequency shifts of up to 200 KHz.