Velocity matched electro-optic phase modulator for wide optical sideband generation

A novel ultrafast and high effective electro-optic phase modulator is reported, in which the velocity matching between light group velocity and microwave phase velocity is achieved by using a higher-order mode of the microstrip line on an electro–optic crystal. This modulator can be used for long interaction length, hence an enormously wide optical sideband with low microwave power can be obtained. In an experiment using a modulator with a 20 mm long modulating electrode on the LiTaO3 crystal, wide optical sideband spectra of 680GHz (FWHM) were generated at 16.2GHz modulation frequency.