DAC-less PAM-4 generation in the O-band using a silicon Mach-Zehnder modulator

International audienceWe demonstrate 20-Gb/s 4-level pulse amplitude modulation (PAM-4) signal generation using a silicon Mach-Zehnder modulator (MZM) in the O-band. The modulator is driven by two independent binary streams, and the PAM-4 signal is thus generated directly on the chip, avoiding the use of power-hungry digital-to-analog converters (DACs). With optimized amplitude levels of the binary signals applied to the two arms of the MZM, a pre-forward error correction (FEC) bit-error rate (BER) as low as 7.6 × 10 −7 is obtained. In comparison with a commercially available LiNbO 3 modulator, the penalty is only 2 dB at the KP4 FEC threshold of 2.2 × 10 −4

25-Gb/s transmission over 2.5-km SSMF by silicon MRR enhanced 1.55-μm III-V/SOI DML

International audienceThe use of a micro-ring resonator (MRR) to enhance the modulation extinction ratio and dispersion tolerance of a directly modulated laser (DML) is experimentally investigated with a bit rate of 25 Gb/s as proposed for the next generation data center communications. The investigated system combines a 11-GHz 1.55-μm directly modulated hybrid III-V/SOI DFB laser realized by bonding III-V materials (InGaAlAs) on a silicon-on-insulator (SOI) wafer and a silicon MRR also fabricated on SOI. Such a transmitter enables error-free transmission (BER<; 10-9) at 25 Gb/s data rate over 2.5-km SSMF without dispersion compensation nor forward error correction (FEC). As both laser and MRR are fabricated on the SOI platform, they could be combined into a single device with enhanced performance, thus providing a cost-effective transmitter for short reach applications