Characteristic of a Broadband Ti:LiNbO, Optical Modulator with Buried Electrodes and Etched Grooves in the Buffer Layer

Traveling wave Ti:LiNbO, Mach-Zehnder optical modulators with buried electrodes and etched grooves in the SiO, buffer layer are analyzed by the finite element method. The tradeofl between the bandwidth BW and the half-waue voltage V, is discussed. The value of BW/V7 is used to weight the total performance of the modulator. Taking a thick buffer layer and etching deep grooves in the buffer layer are demonstrated as two effective methods to improve the performance of the modulator. A 3-dB optical bandwidth of 18 GHz with half-wave voltage 5V at a wavelength of 1.55 p m could be obtained even though the electrode is not very thick. When the requirement of half-wave voltage is not very critical, a bandwidth of more than 100 GHz can be obtained.