A Joint Linearization/Companding Approach for Improving a CO-OFDM Transmitter

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 systems employing a semiconductor optical amplifier. The PAPR reduction is performed via Wang’s nonlinear companding transform, which has been recently pointed out as a pertinent choice for optical communications, and a filter lookup table scheme is considered for linearizing the transmitter. Experimental results prove the effectiveness of the proposed scheme, as a lower error vector magnitude is achieved with respect to system implementations using only the PAPR reduction or linearization.