Optical transmission system equalizer

A signal processing apparatus for processing

• an amplified wavelength division multiplexed lightwave signal
• of at least two channels of information signals, comprising
• a first optical signal power adjuster coupled to control the power of the signal of said first channel and a second optical signal power adjuster coupled to control the power of the signal of said second channel,
• a multiplexer coupled to combine said first and second optical signals into a wavelength-multiplexed signal,
• a demultiplexer coupled to separate a wavelength-multiplexed signal into separate signals,
• first and second detectors coupled to receive the separate signals from said demultiplexer,
• an optical fiber transmission line having at least one optical fiber amplifier interposed between said multiplexer and said demultiplexer,
• processor means coupled to said first and second optical signal power adjusters and said first and second detectors for carrying out an operation represented by a first relationship:
• ##EQU3## where P.sub.new.sup.i is the new input signal power of an information signal of a channel;
• P.sub.TOT is the total signal power;
• T is the total number of channels;
• and
• G.sub.i is the optical gain experienced by the information signal;
• and a second relationship:
• ##EQU4## where P.sub.new.sup.i is the new input signal power of an information signal of a channel;
• P.sub.TOT is the total signal power;
• T is the total number of channels;
• and
• S/N is the signal-to-noise ratio of the information signal.

A signal processing apparatus for processing an amplified wavelength division multiplexed lightwave signal of at least two channels of information signals, comprising

• a first optical signal power adjuster coupled to control the power of the signal of said first channel and a second optical signal power adjuster coupled to control the power of the signal of said second channel,
• a multiplexer coupled to combine said first and second optical signals into a wavelength-multiplexed signal,
• a demultiplexer coupled to separate a wavelength-multiplexed signal into separate signals,
• first and second detectors coupled to receive the separate signals from said demultiplexer,
• an optical fiber transmission line having at least one optical fiber amplifier interposed between said multiplexer and said demultiplexer,
• processor means coupled to said first and second optical signal power adjusters and said first and second detectors for carrying out an operation represented by a relationship:
• ##EQU5## where P.sub.new.sup.i is the new input signal power of an information signal of a channel;
• P.sub.TOT is the total signal power;
• T is the total number of channels;
• S/N is the signal-to-noise ratio of the information signal;
• and
• the wavelength-multiplexed signal has a rate of at least a megabit-per-second.

A signal processing apparatus for processing an amplified wavelength division multiplexed lightwave signal of at least two channels of information signals, comprising

• a first optical signal power adjuster coupled to control the power of the signal of said first channel and a second optical signal power adjuster coupled to control the power of the signal of said second channel,
• a multiplexer coupled to combine said first and second optical signals into a wavelength-multiplexed signal,
• a demultiplexer coupled to separate a wavelength-multiplexed signal into separate signals,
• first and second detectors coupled to receive the separate signals from said demultiplexer,
• an optical fiber transmission line having at least one optical fiber amplifier interposed between said multiplexer and said demultiplexer,
• processor means coupled to said first and second optical signal power adjusters and said first and second detectors for carrying out an operation represented by a relationship:
• ##EQU6## where P.sub.new.sup.i is the new input signal power of an information signal of a channel;
• P.sub.TOT is the total signal power;
• T is the number of channels,
• G.sub.i is the optical gain experienced by the information signal;
• and
• the wavelength-multiplexed signal has a rate of at least a megabit-per-second.