peak power and channel power

"Jack" wrote in news:1133493754.681618.74480 @g44g2000cwa.googlegroups.com:

Are you asking the difference between channel power and full system power, i.e., all channel powers combined? If so, an easy way is to convert dBm powers to mW then add and convert back to dBm.

Dear Moshe,

My question is that what difference of the peak power a specific wavelength and the channel power of this wavelength is.A customer uses our OCM module to monitor the spectrum of their DWDM system and there is a little power difference for every wavelenght between the optical power reported by the OCM and the peak value of the spectrum tested by OCM.

Thanks and B.R.

Jack

Moshe wrote:

That power differnece you mentioned could arise from the fact that the optical signal is not CW, it is modulated instead.

The modulation basically will "spread out" the spectrum of an optical signal. Depending on different modulation formats and data rates, the spectrum of the modulated signal can be so different from the original optical spectrum.

At low data rate (10Gbps or less), your OCM may work in general (for a few different formats). At higher level (40G), the OCM has to be able to deal with each format specificly in order to report power and wavelength correctly, which calls for a much smarter algorithm. Good luck on that.

BR

Jack wrote: