Evaluation of BER and WDM Crosstalk Penalty at 2.5 Gb/s in an SOA by Holding Beam Injection around Transparency Wavelength

We experimentally demonstrate the influence of a high power continuous wave (CW) injection, as a holding beam (HB), into an SOA around the gain transparency wavelength on the bit error rate (BER) of a signal modulated at 2.5 Gb/s traveling through the amplifier. We show that the injection of an HB power of 19 dBm at 1480 nm inside an SOA, in three regimes (absorption, transparency and gain), can reduce the signal BER, mainly, when working at high input signal powers. As a result for a BER of 10^-9, an improvement more than 2.5 dB of input power can be obtained following the HB regime injection. In addition, we use the HB injection in an SOA based multi-channel WDM transmission system to reduce the crosstalk penalty between signals, which is caused by the cross-gain modulation (XGM). Experiment shows that the crosstalk penalty between two signals is suppressed and the SOA induced BER is improved when injecting the HB in the absorption regime. However, this penalty is noticeably reduced by the HB injection in the two other regimes