CWDM Issue.

I am hoping to get some extra suggestions on troubleshooting an strange CWDM issue.

Okay we recently had to move our uplink, and after the migration, we have noticed that one of our wavelengths in the 1510-1590 range that is having massive signal loss, we are seeing -37dbm or lower for a single wavelength. Prior to the migration there was a loopback installed on the Demarc for the provider who saw an expected signal across the complete range. This leads me to believe that the carrier side is alright. Once the CWDM was placed on this new link we lost the wavelength.

Things that were tested.

• Swapped the fiber for the problematic wavelength.
• Swapped Optical modules.
• Swapped ports.
• Installed a Loopback on the problematic wavelength.
• Fiber cleaned.

Things I feel that might be an issue are possibly the CWDM, fiber attenutation.

Can anyone else, come with a suggestion.

I am sorry, I can't be more specific in information.