Fig. 1. Comparison of monolithic TFLN EOMs fabricated by EBL and photolithography.

Fig. 2. (a) Microscope image and (b) cross section of the TFLN traveling-wave Mach–Zehnder EOM.

Fig. 3. Simulated results of (a) the microwave loss (α), (b) the effective index (N_m) of microwave signals, and (c) the characteristic impedance (Z₀) at 100 GHz versus W and G; (d) simulated V_πL versus ridge height and G.

Fig. 4. (a) SEM image of the etched LN waveguides and electrodes before SiO₂ cladding deposition. (b) SEM image of the cross section of the waveguides. (c) AFM measurement of the waveguides. (d) EE S-parameters of the CPW electrodes. (e) Z₀ and N_m of the electrodes extracted from S-parameters in (d).

Fig. 5. EO characterization of the LN modulator: (a) V_π test with 5 MHz triangular voltages sweep. (b) EO S21 measurement result from 10 MHz to 110 GHz, showing an ultra-high bandwidth over 110 GHz.

Fig. 6. Transmission results. (a) Experimental setup for the transmission system. (b) Measured BER performance versus bit rates of PAM-4 and PAM-6 signals. (c), (d) Optical spectrum of different baud rate PAM-4 and PAM-6 signals. (e)–(h) Typical eye diagrams of 50 Gbaud PAM-6, 100 Gbaud PAM-6, 60 Gbaud PAM-4, and 100 Gbaud PAM-4 signals, respectively.