Fig. 1. Cross-sectional schematic diagram of the MZM’s active arms.

Fig. 2. (a) Mode analysis of a rib waveguide with 90 nm slab thickness; the inset is the quasi-TE mode profile; (b) simulated optical loss at wavelength of 1950 nm.

Fig. 3. (a) Loss performance under different PN junction offsets at the voltage of 0 V, 2 V, and 4 V; (b) relationship between Lπ and PN junction offset under a voltage of 2 V and 4 V, respectively; (c) and (d) loss versus intermediate doping separation and heavy doping separation with a voltage of 0 V, 2 V, and 4 V, respectively.

Fig. 4. Depletion width as a function of reverse bias. The inset is the distribution of electrons in the waveguide with a voltage of 0 V, 2 V, and 4 V, respectively.

Fig. 5. (a) Two-dimensional schematic diagram of T-shaped rail electrode structure; (b) electro-electro (EE) S21 parameters of T-shaped traveling-wave electrode.

Fig. 6. Simulated frequency dependent (a) microwave attenuation, (b) microwave index, (c) characteristic impedance, and (d) EO S21 parameters.

Fig. 7. Optical microscope image of the traveling-wave MZM.

Fig. 8. (a) Measured optical transmission and (b) phase shift as functions of reverse bias.

Fig. 9. Schematic diagram of the high-speed measurement setup. PD, photodetector; DSO, digital storage oscilloscope; AWG, arbitrary waveform generator; TDFA, thulium-doped fiber amplifier; PC, polarization controller.

Fig. 10. Eye diagram for MZM at data rate of 30 Gbit/s with OOK modulation.

Fig. 11. BER curves at different modulation rates. Inset: the offline post-FFE eye diagrams of 80 Gbit/s (left) and 60 Gbit/s (right) PAM-4 signals.

Fig. 12. Measured EO S21 response of the 2-μm MZM at −2  V DC bias.

Table 1. Free-Carrier Dispersion and Absorption Coefficients