Fig. 3: Digital CMOS-level electro-optic modulation with non-return to zero (NRZ) pseudorandom bit sequence (PRBS) of 27 bits.
a Setup configuration using a CMOS DAC to drive the ground-signal-ground (GSG) electrodes of the modulator. b Time-domain waveforms measured at the output of the modulator at 5 Gb/s for drive voltages of 2 Vpp and 1.2 Vpp, respectively. c Drive-voltage-dependent eye diagram quality factors (QE) for increasing bit rate. The bar plot shows the modulation bandwidth with QE > 2.7. The high-bandwidth photodiode is directly connected to a real-time oscilloscope for recording eye diagrams and QE without equalization. No low-pass RF filter is used in the measurement. d Measured eye diagrams and QE at 5 Gbit/s for different drive voltages. A low-pass RF filter is used at the output of the photodiode for inter-symbol-interference reduction. A low-pass RF filter is used at the output of the photodiode for inter-symbol-interference reduction. Eye diagrams and QE are measured via the oscilloscope without equalization. BER is estimated from the measured QE factor30,31. Scale bars, 33 ps.
