Active-Width Control in EMBH DFB Lasers.

We have used the Monte-Carlo technique to obtain the distribution of the active width resulting from intrawafer and interwafer variations in the etch and the growth parameters. The distribution is found to be nearly Gaussian whose standard deviation sigma depends on the range over which the growth parameters are allowed to vary. We have performed a sensitivity analysis to see how sigma varies with the allowed range of the growth parameters. Using realistic values of the etch and the growth parameters, we estimate that the 3-step etch process should provide a yield of 85-90% for the specified range 0.7-1.5micron for the active width. The experimental distribution of the active width is in good agreement with the theoretical model. The PBCT measurements of kink powers for 146 laser chips show that only 16.4% lasers have kinks below 5 mW level, suggesting that the active-width variations are not likely to be a major source of kink-related drop in the laser yield.