DYNAMIC AND CW LINEWIDTH MEASUREMENTS OF 1.55-MU-M INGAAS INGAASP MULTIQUANTUM WELL DISTRIBUTED FEEDBACK LASERS

Measurements of the CW linewidth, and frequency chirp as a function of modulation data rate and bias level for the 1.55-mu-m InGaAsP multiquantum well distributed feedback lasers grown by low-pressure MOCVD are presented. The results show that the CW linewidth of the asymmetric facet coated multiquantum well DFB lasers can be as low as 2.0 MHz at 13.5 mW output power. The frequency chirp increases with modulation data rate and is significantly larger if the laser off-state is below threshold than if it is above threshold. The 20 dB down chirp widths are in range of 1.9-5 angstrom for 40 mA peak to peak modulation current at 10 Gb/s under above threshold bias.