Low Switching Voltage Mach–Zehnder Modulator Monolithically Integrated With DFB Laser for Data Transmission up to 107.4 Gb/s

We present a transmitter optical subassembly consisting of an InP-based travelling wave electrode Mach-Zehnder modulator monolithically integrated with a distributed feedback laser. At 56-Gb/s non-return-to-zero ON/OFF keying (NRZ-OOK), we achieve 3.5-km transmission before breaking the hard decision forward error correction threshold (3.8 ×10^-3). 9-km transmission is achieved at 71.6-Gb/s 4-pulse-amplitude modulation (PAM4) and 5 km at 107.4 Gb/s PAM8. The modulation voltage is between 1.5 and 2 V, leading to overall power consumption of 171 mW for the NRZ-OOK case and 206 mW at PAM4 and PAM8.