Nonlinear Distortion Analysis of Directly Modulated ... - 연세대학교

these suppression values are dependent on the external light power anddetuning frequency, more distortion suppression can be possible at differentcondition.Then, the relaxation oscillation frequency increase phenomenon issimulated. This is a main cause of distortion suppression. From the systemmatrix, eqn. 3-3, the laser frequency response can be derived. Fig. 3-4 showsthe relaxation oscillation frequency increase very well. It is a proof ofdistortion suppression by injection locking. As the injection light powerincreases, the relaxation oscillation frequency increases more. Detailedexplanations will be given in section III-C.B. Stable Locking Range according to the Laser ParametersAs explained in section III-A, to reduce the laser nonlinear distortion, thestable locking condition should be satisfied for injection locking application.This stable locking range is greatly influenced by intrinsic laser parameters.Therefore, by comparing these phenomena, laser parameter effects to thelocking property can be analyzed. To acquire stable locking range, thesimulation method in section III-A is also used.First, the nonlinear gain suppression factor is considered. This is generallybelieved the result of spectral hole burning and carrier heating [19, 20]. Fig. 3-5 shows the stable locking range with gain suppression factor and without it.As can be seen in the figure, when the gain suppression factor exists, the stablelocking range is greatly increased. This is because the nonlinear gainsuppression factor effect is found to cause increased damping of the relaxation28