Wavelength-division multiplexing optical transmission system and optical communication method

The wavelength-division multiplexing optical transmission system as claimed in clain 14, wherein, at any wavelength “λ”, said compensating-purpose dispersion D2 satisfies an equation given by:

• D2(λ0)+0.4{D1(λ0)−D1(λ)}≦D2(λ)≦D2(λ0)+0.6{D1(λ0)−D1(λ)}.

The wavelength-division multiplexing optical transmission system as claimed in clain 23, wherein, at any wavelength “λ”, said compensating-purpose dispersion D2 satisfies an equation given by:

• D2(λ0)+0.4{D1(λ0)−D1(λ)}≦D2(λ)≦D2(λ0)+0.6{D1(λ0)−D1(λ)}.

A dispersion-compensating device for performing a dispersion compensation to a wavelength-division multiplexing optical signal to be transmitted through an optical transmission path from a transmitter terminal to a receiver terminal,

• wherein said dispersion-compensating device provides a compensating-purpose dispersion D2 to said wavelength-division multiplexing optical signal, and
• wherein said compensating-purpose dispersion D2 satisfies conditions that at any wavelength “λ” included in said transmission wavelength band, if dD1(λ)/dλ≠0 is established, then {dD1(λ)/d λ}×{dD2(λ)/dλ}<0 is also established, and if dD1(λ)/dλ=0 is established, then dD2(λ)/dλ=0 is also established, where D1 represents a dispersion generated in said wavelength-division multiplexing optical signal during when said wavelength-division multiplexing optical signal is transmitted through said transmission path from said transmitter terminal to said receiver terminal.

A dispersion-compensating device for performing a dispersion compensation to a wavelength-division multiplexing optical signal to be transmitted through an optical transmission path from a transmitter terminal to a receiver terminal,

• wherein said dispersion-compensating device provides a compensating-purpose dispersion D2 to said wavelength-division multiplexing optical signal, and
• wherein over said transmission wavelength band, a sign of a dispersion slope of said compensating-purpose dispersion D2 is opposite to a sign of a dispersion slope of a dispersion D1 generated in said wavelength division multiplexing optical signal, during when said wavelength division multiplexing optical signal is transmitted through said transmission path from said transmitter terminal to said receiver terminal, provided that, at a wavelength where said dispersion slope of said dispersion D1 is zero, said dispersion slope of said dispersion D2 is also substantially zero.

A dispersion-compensating device for performing a dispersion compensation to a wavelength-division multiplexing optical signal to be transmitted through an optical transmission path from a transmitter terminal to a receiver terminal, said dispersion-compensating device including:

• an optical circulator coupled between said optical multiplexer and said transmitter terminal;
• and
• a fiber Bragg grating coupled to said optical circulator for receiving said wavelength-division multiplexing optical signal through said optical circulator from said optical multiplexer and performing said dispersion compensation to said wavelength-division multiplexing optical signal, and said fiber Bragg grating has a variation in a grating pitch Λ which is represented by first and second grating pitch functions Λ1(x) and Λ2(x) smoothly and continuously bounded to each other via a reverse curve point, at which said grating pitch Λ is equal to a critical grating pitch Λ1, and said first grating pitch function Λ1(x) is represented by a first curve being arched upwardly in a first grating pitch range where said grating pitch Λ is smaller than said critical grating pitch Λ1, while said second grating pitch function Λ2(x) is represented by a second curve being arched downwardly in a second grating pitch range where said grating pitch Λ is larger than said critical grating pitch Λ1.

A method of performing a dispersion compensation to a wavelength-division multiplexing optical signal to be transmitted through an optical transmission path from a transmitter terminal to a receiver terminal,

• wherein said dispersion compensation is made by providing a compensating-purpose dispersion D2 to said wavelength-division multiplexing optical signal, and
• wherein said compensating-purpose dispersion D2 satisfies conditions that at any wavelength “λ” included in said transmission wavelength band, if dD1(λ)/dλ≠0 is established, then {dD1(λ)/d λ}×{dD2(λ)/dλ}<0 is also established, and if dD1(λ)/dλ=0 is established, then dD2(λ)/dλ=0 is also established, where D1 represents a dispersion generated in said wavelength-division multiplexing optical signal during when said wavelength-division multiplexing optical signal is transmitted through said transmission path from said transmitter terminal to said receiver terminal.

A method of performing a dispersion compensation to a wavelength-division multiplexing optical signal to be transmitted through an optical transmission path from a transmitter terminal to a receiver terminal,

• wherein said dispersion compensation is made by providing a compensating-purpose dispersion D2 to said wavelength-division multiplexing optical signal, and
• wherein over said transmission wavelength band, a sign of a dispersion slope of said compensating-purpose dispersion D2 is opposite to a sign of a dispersion slope of a dispersion D1 generated in said wavelength division multiplexing optical signal, during when said wavelength division multiplexing optical signal is transmitted through said transmission path from said transmitter terminal to said receiver terminal, provided that, at a wavelength where said dispersion slope of said dispersion D1 is zero, said dispersion slope of said dispersion D2 is also substantially zero.