摘要： There is a growing research interest towards high-capacity communication systems for inter data-center (~80 km) communications. While coherent systems are a mature and high-performance technology, their cost is still very high compared to simpler direct-detection solutions. Recently, advanced digital signal processing (DSP) techniques, such as Single Side-Band (SSB) transmission and Kramers-Kronig (KK) receivers have been proposed to increase both spectral efficiency and reach of such direct-detection systems. Apart from the DSP techniques, the main drawback of these solutions is the requirement of a strong (i.e. several decibels higher than the signal) carrier added at the transmitter. This solution inevitably decreases the resulting signal-to-noise ratio (OSNR) and potentially increase the impact of fiber Kerr non-linearities. In this contribution, will provide further insights on the practical implementation penalties which arise from the addition of such carrier in the framework of single-sideband DMT solutions. In particular, we will focus on the modulator biasing technique to add such carrier.