Performance and Characterization Comparison of QD SOA, QW SOA, Bulk SOA and PDFA for Multi-Tbps O-Band WDM Links

Due to the exponential growth of internet traffic, the demand for increased capacity for inter and intra-datacenter interconnects is pushing the adoption of coherent and WDM transceivers in the O-band. Semiconductor optical amplifiers are a popular choice of amplifying technology for datacenter applications, but the choice of active region technology (QD, QW and Bulk) remains unclear for signal amplification. This article presents a qualitative and quantitative comparison of SOA and fiber amplifier characteristics and performance for IM/DD and coherent transmission systems operating at the Tbps capacities required for the next generation of optical transceivers. First, we discuss the advantages of QD for SOAs. Next, we quantify key SOA performance metrics for QD, QW and bulk SOA technologies. The QD SOA demonstrates an input saturation power of +4.1 dBm, a small signal gain of 18.2 dB, a noise figure of 5.6 dB and an $\alpha$ -factor of 0.86-1.2. Finally, a high speed transmission performance analysis is presented for single-wavelength and WDM configurations for both IM/DD and coherent transmission. The QD SOA outperformed all other amplifiers for both IM/DD and coherent. Notably, the QD SOA enabled 432Gbps using 180 GBaud PAM8 under the 25% overhead SD-FEC threshold and was the only amplifier to achieve 1.6 Tbps for coherent transmission under the same FEC threshold at 10km. These results underscore the exceptional advantage of QD for SOAs highlighting its potential for future high-capacity optical networks operating in both IM/DD and coherent across single or multiple wavelengths.