Fig. 1. Schematics of the hybrid LN modulator with silicon TOPS. (a) Schematic of the whole structure. The insets are optical mode profiles of modulation and the TOPS region. (b) Perspective view of the TOPS. (c) Cross-section view of the high-speed modulation region and TOPS.

Fig. 2. Simulated and experimental results of characteristic impedance Z0, group index ng, and microwave attenuation αm for TWE. The black dashed lines represent the 50 Ω impedance and group index of the optical mode, respectively.

Fig. 3. Scanning electron microscopy (SEM) images of the modulator. (a) SEM image of the cross section of the high-speed modulation region. (b) SEM image of the cross section of TOPS. Both sections are formed by the focused ion beam (FIB) process.

Fig. 4. Experiments of the drift of the operating point for EOPS and TOPS bias control methods. (a) Transmission as a function of applied voltage on TOPS. (b) Power shift for TOPS and EOPS cases as a function of time. (c) Schematic of the experimental setup. The signals from the analog signal generator are set to 10 MHz. (d) Measured SHD intensity variations as a function of time. The red and blue curves correspond to the time-dependence change of SHD for TOPS and EOPS bias control, respectively. (e) Frequency response at the beginning of measurements for both two bias methods. (f), (g) Frequency response for the EOPS and TOPS bias control methods after operating for 2 h, respectively.

Fig. 5. EO performance of hybrid Si and LN modulator. (a) Normalized optical transmissions as a function of the applied voltage on TWE. (b) EO bandwidth (S21 parameter) for the modulator.

Fig. 6. High-speed transmission experiments. (a), (b) Optical eye diagrams for OOK signal at data rates of 84 Gb/s and 100 Gb/s. (c), (d) Measured PAM-4 modulation optical eye diagrams at 53 Gbaud (106 Gb/s) and 64 Gbaud (128 Gb/s). (e) Measured curves of BER versus the received optical power for 53 Gbaud (106 Gb/s) and 64 Gbaud (128 Gb/s) PAM-4 signals.