Patent ID: 7460784

Claim:
A method of pre-emphasizing an optical multiplex signal comprising a plurality of signals having different wavelengths, the plurality of signals transmitted from a transmitter to a receiver, the method comprising: determining an avenge power for the signals to be transmitted to the receiver; determining a first current power of the signals at the transmitter; determining a second current power of the signals at the receiver; determining new power values from the first and second current powers and the average power; and adjusting a transmitting power of the transmitter according to the new power values, wherein determining the new power values is based on equalizing signal-to-noise ratios of the signals received at the receiver, wherein the plurality of signals is optically transmitted over N+1 optical amplifiers connected in series and having substantially equal amplification characteristics, and over N transmission links connecting the N+1 optical amplifiers, and wherein the new cower values regarding at least one of the plurality of signals transmitted over the N+1 optical amplifiers are determined according to the following formula: P IN ⁡ ( λ ) ⁢ _new := < P IN > · Q ⁡ ( λ ) < Q ⁡ ( λ ) > ⁢ { in ⁢ ⁢ mW } , wherein <Pin> designates the average power of the at least one signal at the transmitter, and wherein, for tolerating a balance of the signal-to-noise ratios of the signals received at the receiver, the function Q(λ) is defined as follows: Q ⁡ ( λ ) < Q ⁡ ( λ ) > = k ⁢ f ⁡ ( λ ) λ · 1 N + 1 · G LINK - 1 G LINK N N + 1 · [ G LINK 1 N + 1 - 1 ] , wherein G LINK is an overall gain of a channel determined from the first and second current powers, f(λ) is a spectral number function of the optical amplifiers, and K is a constant.