Patent ID: 8750722

Claim:
A method, comprising: transmitting a first wavelength division multiplexed optical signal on an optical communication path, the first wavelength division multiplexed optical signal including first optical signals having a first modulation format; transmitting a second wavelength division multiplexed optical signal on the optical communication path, the second wavelength division multiplexed optical signal including selected ones of the first optical signals and second optical signals, each of the second optical signals having a second modulation format different than the first modulation format; and transmitting a third wavelength division multiplexed optical signal on the optical communication path, the third wavelength division multiplexed optical signal including selected ones of the second optical signals and third optical signals, the third optical signals having a third modulation format different than the first and second modulation formats, wherein the first modulation format has an associated first noise margin, the second modulation format has an associated second noise margin and the third modulation format has an associated third noise margin, the first noise margin being greater than the second noise margin and the second noise margin being greater than the third noise margin, and the method further including: transmitting a fourth wavelength division multiplexed optical signal on the optical communication path, the fourth wavelength division multiplexed optical signal including selected ones of the third optical signals and fourth optical signals having a fourth modulation format different than the first, second, and third modulation formats.