On the assessment of transmission performance of external-cavity semiconductor lasers

The performance of an intensity modulated direct detection transmission system using an external cavity semiconductor laser (ECL) transmitter, for bit-rates of 2.5 and 5Gbit/s, predicted by using two ECL models is investigated. Results reveal that the transmission performances predicted by the two models can be remarkably different, even at bit rates as low as 2.5Gbit/s, and the discrepancies on the transmission performance are mainly due to the significantly different ECL frequency chirp predicted by each model. Since these discrepancies are attributed to the low-frequency approximation used to derive the approximated model, the rigorous model must be used to assess more accurately the transmission performance of ECLs.