Improved electrooptic modulator with ridge structure in X-cut LiNbO/sub 3/

A ridge-type Mach-Zehnder modulator on X-cut LiNbO/sub 3/ is fabricated by wet etching with proton-exchange pretreatment. Experimental results show that, with the assistance of the ridge structure, the drive voltage of the proposed modulator is reduced. The enhancement of overlap integral caused by ridge structure is also validated from numerical simulation. Moreover, an improved design to further reduce the drive voltage of the ridge-type Mach-Zehnder is proposed by a proper placement of waveguide relative to the electrode.