CNR limitations of Er-doped optical fiber amplifiers in AM-VSB video lightwave trunking systems

The CNR limitations of two different types of 980-nm pumped in-line Er-doped optical fiber amplifiers with the same small-signal noise figure to transport multichannel AM-VSB video signals is studied. Experimental results and frequency-domain simulations suggest that the noise figure of a high-power in-line erbium-doped fiber amplifiers (EDFA) should be 5 dB or less when operating deep in saturation (optical input power +3 dBm). Using two such in-line amplifiers produced an AM CNR greater than 50 dB with negligible CSO and CTB distortion degradation for a lightwave trunking link transporting 71 AM-VSB video channels with a total optical link budget of 39 dB. These results can clarify the EDFA selection criteria for AM video lightwave links.