Bit Error Rate in WDM Data Transmission Links With Semiconductor Optical Amplifier

We show experimentally that a semiconductor optical amplifier (SOA) can be used for amplification of WDM optical signals with PAM4 and NRZ modulation at bit rates as high as 400 Gb/s for a broad range of input powers without inducing significant amount of errors. The effect of SOA on the bit error rate (BER) is analysed as a function of SOA input power, current, baud rate and number of optical channels. We develop a theory providing an analytical expression for the BER in links with SOA for any intensity modulation direct detect (IM/DD) format. The model accounts for all experimental findings and suggests applicability of state of the art SOAs for data transmission at the bit rates as high as several Terabits per second. The SOA-induced BER is mainly determined by the noise figure at low input powers and SOA saturation power at high input powers, and we provide simple criteria for SOA applicability for data transmission based on these parameters.