Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)The erasing of optical carrier intensity modulation and posterior data rewriting are analyzed for two semiconductor optical amplifiers with different active lengths: 2 mm and 8 mm long.Input signal extinction ratios (ERin) varying from 3.5 dB up to 10 dB are tested for the downstream channel at different bit rates (from 7 Gb/s up to 56 Gb/s), followed by remodulation of the upstream channel at 7 Gb/s. The ultra-long 8 mm device shows superior performance, working error-free for bit rates up to 30 Gb/s, with negligible power penalties for moderate ERin. However, for high bit rates (>40 Gb/s) and high input extinction ratios (ERin = 10 dB), the 8 mm device shows error-floor at BER = 106. In comparison, even for moderate ERin at 40 Gb/s, the 2 mm device already presents error-floors at BER = 103. (c) 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:9981001, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.274965559981001Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)CNPq [2007/56024-4]FAPESP [2007/56024-4]FAPESP [2005/51689-2, 2009/08537-8]