International audience—The joint use of peak-to-average power ratio (PAPR) reduction and linearization via digital predistortion is investigated in this letter, with the view to improve the performances of coherent optical OFDM (CO-OFDM) systems employing a semiconductor optical amplifier (SOA). PAPR reduction is performed via Wang's nonlinear companding transform (WNCT), which has been recently pointed out as a pertinent choice for optical communications, and a Filter Lookup Table (FLUT) scheme is considered for linearizing the transmitter. Experimental results prove the effectiveness of the proposed scheme, as a lower EVM is achieved with respect to system implementations using only PAPR reduction or linearization

International audienceCoherent-Optical OFDM systems are known to be sensitive to large peak-to-average power ratio (PAPR) at the transmitter output, due to nonlinear properties of some components involved in the transmission link. In this paper, we investigate the impact of an amplification of such signals via a semiconductor optical amplifier (SOA), considering some recent experimental results. An efficient tradeoff between BER performance, computational complexity and power efficiency is performed by a proper design of Wang's nonlinear companding function, considered for the first time in an optical communication context. A BER advantage of around 3 dB can hence be obtained over a standard system implementation not using PAPR reduction. The designed function also proves to be more efficient than µ-law function, considered in the literature as an efficient companding scheme

Semiconductor Optical Amplifiers are known to be prone to nonlinear effects in the saturated regime. This is particularly true if the signals to be amplified have a non-constant envelope and a high Peak-to-Average Power Ratio (PAPR). The benefits of envelope-tracking is investigated here for linearizing a Coherent-Optical OFDM (CO-OFDM) transmitter employing a SOA as a power booster. The effect of a filtered envelope is studied and its optimum amplification gain is evaluated by considering an accurate physical model of the SOA. Moreover, the joint combining of PAPR reduction (via nonlinear companding) and envelope tracking is proved to be effective, with a power margin close to 5 dB.