• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.37 no.11
• /
• pp.50-58
• /
• 2000

A Mach-Zehnder type $Ti:LiNbO_3$ optical modulator with a grooved $SiO_2$ buffer layer, was evaluated in terms of an electrode structure. The finite element method was performed to find out the optinum design parameters of electrodes. characteristic impedance ($Z_o$), MW effective index ($N_{eff}$) and attenuation constant ($a_o$)of fabricated traveling-wave electrodes were measured and compared with those obtained by the simulation expectation. For an optical modulator with 11${\mu}m$thick electrodes and a grooved $SiO_2$ buffer layer, the 3dB bandwidth based on the RF measurement results turned out to be 18GHz.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.39 no.7
• /
• pp.26-36
• /
• 2002

Mach-Zehnder type traveling-wave optical modulators with 3-section and 5-section phase reversal were designed and fabricated on z-cut $LiNbO_3$ substrates. Optical waveguides were designed by means of the FDM(Finite Difference Method). Design of CPW traveling-wave electrodes were performed by the SOR(Successive Over Relaxation) in the active region and by the CMM(Conformal Mapping) in the input/output section. The optical response R(${\omega}$ calculated based on the measured S-parameters showed the bandwidth of 15GHz centered at 25GHz for the 3-section, and the bandwidth of 22GHz at 45GHz for the 5-section.