Threshold gain difference requirements for nearly single-longitudinal-mode lasers

The performance implications of mode partition fluctuations in nearly single longitudinal mode lasers are examined in a comprehensive manner using a technique which utilizes a simulation-based method to determine the partitioning statistics and a formula-based method to evaluate the bit error ratio. Utilizing a truncated pulse train, Gauss quadrature rule method, it is possible to accommodate many features unique to the problem of assessing the performance implications of mode partitioning. For several systems, the required value of the threshold gain difference between the lasing mode and the dominant side mode is determined. For 2.4 Gb/s NRZ modulation, the threshold gain difference requirement increases from 3 cm^-1 to 7 cm^-1 as the bias current of the laser decreases from 1.1 to 0.9 times the laser threshold current. For 4.8 Gb/s NRZ modulation, the threshold gain difference requirement increases from 5^-1 to 8 cm^-1 as the bias current of the laser decreases from 1.2 to 1.01 times the laser threshold current. The threshold gain difference requirement has been found to be more stringent for the RZ encoding format