Search for the Cause of Asymmetric Results of Monitoring Errors in DWDM Filters and the Benefits of Corrections in the Last Two Layers

In previous reports on the sensitivity to layer thickness errors of DWDM and similar narrow band filter coatings, it was noted that the effect of monitoring errors that occur before the turning point appear more severe than those that occur after it. No satisfactory explanation had been found for this result. We report on the search for the explanation of that and related findings. The previous simulations did not deal with final corrections that might be made in the last two antireflection layers in the deposition of the design. We now also simulate those final layer adjustments, show how they might be done, and show the benefits that may be obtained.