Gain-loss tradeoff in the performance of high index modulation Bragg filters

Abstract

In this article we explain the gain-loss trade-off by studying the effect of the etching depth l on the reflectivity R and the losses related to optical filters based on Bragg grating (BG). This study has demonstrated that from an optimal modulation depth the desired transfer function of the filter can be the most appropriate in terms of performance. We were also able to experimentally calculate this optimal engraving depth on several realizations. This made it possible to show that once the reflectivity reaches its maximum value, it is useless to exceed this depth value because it does not improve the reflection gain but it only increases the losses related to the BG. This increase in losses leads to the degradation of the quality of the transmission by increasing the probability of error and decreasing the bit rate.