Wavelength division multiplexing optical transmission system and wavelength dispersion compensation unit

A wavelength dispersion compensation unit comprising:

• a wavelength division section comprising:
• a first three-port bandpass filter dividing a wavelength-multiplexed signal transmitted through an optical transmission line into contiguous groups including a first medium bandwidth group of signals, a first shorter wavelength side end group of signals on a shorter wavelength side of the first medium bandwidth group of signals and a first longer wavelength side end group of signals on a longer wavelength side of the first medium bandwidth group of signals, and
• a second three-port bandpass filter dividing the first medium bandwidth group of signals into contiguous groups including a second medium bandwidth group of signals, a second shorter wavelength side end group of signals on a shorter wavelength side of the second medium bandwidth group of signals and a second longer wavelength side end group of signals on a longer wavelength side of the second medium bandwidth of signals;
• and
• a dispersion compensation section collectively performing dispersion compensation of at least one of:
• the first shorter wavelength side end group of signals and the first longer wavelength side end group of signals taken together without the first medium bandwidth group of signals, and
• the second shorter wavelength side end group of signals and the second longer wavelength side end group of signals taken together without the first shorter wavelength side end group of signals, the first longer wavelengths side end group of signals and the second medium bandwidth group of signals,
• to thereby compensate residual dispersion of the optical transmission line.

An apparatus comprising:

• a first three-port bandpass filter dividing a wavelength-multiplexed signal transmitted through an optical transmission line into contiguous groups including a first medium bandwidth group of signals, a first shorter wavelength side end group of signals on a shorter wavelength side of the first medium bandwidth group of signals and a first longer wavelength side end group of signals on a longer wavelength side of the first medium bandwidth group of signals;
• a second three-port bandpass filter dividing the first medium bandwidth group of signals into contiguous groups including a second medium bandwidth group of signals, a second shorter wavelength side end group of signals on a shorter wavelength side of the second medium bandwidth group of signals and a second longer wavelength side end group of signals on a longer wavelength side of the second medium bandwidth of signals;
• and
• a dispersion compensation section collectively performing dispersion compensation of at least one of:
• the first shorter wavelength side end group of signals and the first longer wavelength side end group of signals taken together without the first medium bandwidth group of signals, and
• the second shorter wavelength side end group of signals and the second longer wavelength side end group of signals taken together without the first shorter wavelength side end group of signals, the first longer wavelengths side end group of signals and the second medium bandwidth group of signals.

An apparatus comprising:

• a first three-port bandpass filter dividing a wavelength-multiplexed signal transmitted through an optical transmission line into contiguous groups including a first medium bandwidth group of signals, a first shorter wavelength side end group of signals on a shorter wavelength side of the first medium bandwidth group of signals and a first longer wavelength side end group of signals on a longer wavelength side of the first medium bandwidth group of signals,
• a second three-port bandpass filter dividing the first medium bandwidth group of signals into contiguous groups including a second medium bandwidth group of signals, a second shorter wavelength side end group of signals on a shorter wavelength side of the second medium bandwidth group of signals and a second longer wavelength side end group of signals on a longer wavelength side of the second medium bandwidth of signals;
• and
• means for collectively performing dispersion compensation of at least one of:
• the first shorter wavelength side end group of signals and the first longer wavelength side end group of signals taken together without the first medium bandwidth group of signals, and
• the second shorter wavelength side end group of signals and the second longer wavelength side end group of signals taken together without the first shorter wavelength side end group of signals, the first longer wavelengths side end group of signals and the second medium bandwidth group of signals.