Level coding technique for a wavelength-division-multiplexed optical access system using a remodulation scheme

• Published in: Optics letters Vol. 37; no. 19; p. 4137
• Main Authors: Guo, Qi, Tran, An V
• Format: Journal Article
• Language: English
• Published: United States 01.10.2012
• ISSN: 1539-4794
• DOI: 10.1364/OL.37.004137

In the wavelength-division-multiplexed optical access network, the system architecture based on remodulating the downstream (DS) signal for upstream transmission resolves the issues of wavelength management and hardware cost . However, this amplitude remodulation scheme introduces intensity noise in the uplink and leads to a system performance penalty. Therefore, the DS extinction ratio (ER(d)) has to be optimized in order to balance the performance of up- and down- links. In this Letter, a novel technique is presented to overcome the restrictions on ER(d) by introducing correlations into the levels of the DS signal to alter its spectrum. 4 dB improved tolerance to ER(d) is achieved in the proposed system. The level-correlation coding technique is also able to mitigate the in-band crosstalk induced by Rayleigh backscattering. It is demonstrated that the system reach is extended by 40 km with the proposed approach.