Design and fabrication of sidewalls-extended electrode configuration for ridged lithium niobate electrooptical modulator

A ridged lithium niobate electrooptical (EO) modulator with low driving voltage and reduced size is proposed. In particular, the electrodes of the proposed device are extended to the sidewalls of the ridge slopes to make the electric and optical fields much more overlapped than those reported. For a more detailed simulation, the electric and optical fields involved in the overlap integral are numerically calculated rather than by using approximate analytic solutions. Experimental results show that the half-wave voltage is reduced by at least 15% in comparison to that of an EO modulator without extended electrode configuration. As both the electrode length and gap are decreased, the device sizes can be reduced by about 18%.