100 GBaud DSP-free PAM-4 optical signal generation using an InP-DHBT AMUX-driver and a Thin-Film Lithium Niobate Modulator Assembly

In this article, we report on the generation of 100-GBd (200-Gb/s) 4-level pulse-amplitude modulation (PAM-4) optical signal, without any support of digital signal processing (DSP) nor off-line equalisation. This is achieved in using an uncooled indium phosphide (InP) analog-multiplexer (AMUX)-driver and a thin film lithium niobate (TFLN) Mach-Zehnder modulator (MZM) assembly, with a -3-dB electro-optical bandwidth in excess of 85 GHz. This result paves the way for low-power DSP-free beyond-1-Tb/s transceivers for next generation optical communication systems and 6G applications. We also present the design and characterisation of the AMUX-driver integrated circuit (IC). The InP-DHBT IC shows a 2-Vppd output swing at 100 GBd in PAM-4 while operating at a 100-GSa/s sampling-rate.