A New TransAtlantic Cable System

Tue Oct 5 17:32:46 UTC 2010

>> Would it be possible to extract via PLL or similar the source clock
>> and use that to modulate the amplifier power?

> Although you can amplify just a single wavelength with an EDFA (has to be in the 1550nm range, not 1310nm), most deployments are using EDFAs in a DWDM environment.  The C-band alone consists of ~5THz (5000GHz) of spectrum between 191.00-195.95 Thz.  Some systems pack 40 wavelengths into this space at 100GHz spacing, some 80 channels @ 50GHz spacing, others 160 @ 25GHz.  Each of these signals is independent, they can each be using different modulation/bitrate/etc.  The amplifiers are completely ignorant to what is going on with each channel, only the devices performing conversion back to the electrical domain need to care about these details (after the incoming light has been demultiplexed into individual signals, of course).

I'm wondering if it could be done per wavelength?
I guess that would be pretty ridiculous having demux + 160 * decoder +
160 * efda + mux..
Just wondering if the theory works though?