NOISE-ANALYSIS FOR OPTICAL FREQUENCY-CONVERSION USING NEARLY DEGENERATE 4-WAVE-MIXING IN SEMICONDUCTOR OPTICAL AMPLIFIER

For future wavelength division multiplexed networks, optical frequency conversion is a very favorable technique which enables the flexible and efficient use of optical frequency bandwidth, however the signal degradation at frequency converters limits the maximum size of the network. Noise in optical frequency conversion using nearly degenerate four wave mixing in a semiconductor optical amplifier has been investigated for the first time. And it is found that the crosstalk from one of the two pump lasers can cause the power penalty on bit error rate (BER) characteristics after optical frequency conversion. Analytical expressions of BER are developed to evaluate the receiver sensitivity penalty caused by optical frequency conversion, and using them for calculation, the optimal setting of the frequency difference between the signal and the pump lasers and the power ratio of two pump lasers are discussed. And a 155-Mb/s FSK transmission with 1750-GHz (14 nm) optical frequency conversion is performed using a novel phase noise cancellation method. The BER performance is in good agreement with the calculated results.