Although EDFAs have been widely accepted in WDM applications, a significant issue regarding its use still remains. Since EDFA gain is wavelength-dependent, and a small gain imbalance is unavoidable, self-filtering in a chain of cascaded EDFAs resulting in a large variation of the signal power and SNR in WDM systems occur. This indicate that it is impossible to get an absolute flat gain with the use of only one EDFA having a particular inversion status. In this article, a simple solution to this problem is presented. The proposed approach involves the alternative employment of high-inversion and medium-inversion EDFAs having different self-filtering wavelengths. By using this approach, the self-filtering effect at peak wavelengths could be mitigated, while the ASE peak around 1530nm is removed without inserting any additional optical filters.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Electrical and Electronic Engineering