Proposal for high extinction ratio LiNbO₃ optical waveguide cutoff modulator

A novel design of an optical waveguide cutoff modulator is proposed. The attenuation of the guided mode in the optical waveguide is controlled by a voltage applied to the coplanar waveguide electrodes deposited on the top of the optical waveguide. An S-shaped optical waveguide structure with a corresponding curved coplanar waveguide electrode is used to increase the extinction ratio and decrease the radiation loss from the curved waveguide. The performance of the device is analysed using the finite difference beam propagation method. Simulation results show that, at an operating wavelength of 1.3 μm, an extinction ratio of over 30 dB can be achieved with applied voltages of ± 10 V.