Optical amplifying-repeating transmission system

An optical amplifying-repeating transmission system, comprising:

• an optical transmitting device for transmitting a lightwave signal with digital information added to return-to-zero lightwave pulses, an optical receiving device for receiving the transmitted lightwave signal, an optical fiber for transmitting of the lightwave signal interconnecting said transmitting device and said receiving device, and a plurality of optical amplifying repeaters disposed spaced on said optical fiber,
• a mean value of wavelengths at which the wavelength dispersion of said optical fiber is zero being smaller that the wavelength of said lightwave signal which is transmitted over said system;
• an accumulated wavelength dispersion value of said optical fiber increasing with the distance of transmission considered macroscopically;
• said optical fiber for transmitting of the lightwave signal being divided into a plurality of sections;
• in accordance with an accumulated wavelength dispersion value of said optical fiber in each section except the last one, a wavelength dispersion medium, locally changing the wavelength dispersion effective to cancel the accumulated wavelength dispersion in the section concerned at the wavelength of said lightwave signal, being disposed in said section.

An optical amplifying-repeating transmission system, comprising:

• an optical fiber for transmitting a lightwave signal with digital information added to return to zero lightwave pulses and a plurality of optical amplifying repeaters disposed spaced on said optical fiber,
• a mean value of wavelengths at which the wavelength dispersion of said optical fiber is zero being smaller than the wavelength of said lightwave signal which is transmitted over said system;
• an accumulated wavelength dispersion value of said optical fiber increasing with the distance of transmission, from a macroscopic viewpoint;
• said optical fiber for transmitting the lightwave signal being divided into a plurality of sections;
• in accordance with the accumulated wavelength dispersion value of said optical fiber in each section except the last one, a wavelength dispersion medium, locally changing the wavelength dispersion in the section concerned at the wavelength of said lightwave signal, being disposed in said section;
• optical outputs of said plurality of optical amplifying repeaters being set to a value larger than an optical output value at which a pulse width compression effect by the nonlinear optical effect of said optical fiber balances with the pulse width expansion effect by its wavelength dispersion produced when said dispersion medium is not used.

An optical amplifying-repeating transmission system, comprising:

• an optical fiber for transmitting a lightwave signal with digital information added to return-to-zero lightwave pulses and a plurality of optical amplifying repeaters disposed on said optical fiber,
• a mean value of wavelengths at which the wavelength dispersion of said optical fiber is zero being smaller than the wavelength of said lightwave signal which is transmitted over said system;
• an accumulated wavelength dispersion value of said optical fiber increasing with the distance of transmission considered macroscopically;
• said optical fiber for transmitting the lightwave signal being divided into a plurality of sections;
• in accordance with the accumulated wavelength dispersion value of said optical fiber in each section except the last one, a wavelength dispersion medium, locally changing the wavelength dispersion effectively to cancel the accumulated wavelength dispersion in the section concerned at the wavelength of said lightwave signal, being disposed in said section;
• said lightwave signal having a wavelength of about 1.5 .mu.m, said optical fiber for transmission being a dispersion-shifting optical fiber whose average wavelength dispersion value is anomalous dispersion, and said wavelength dispersion medium being an optical fiber having a zero wavelength dispersion included in a 2 to 3 .mu.m wavelength band and whose wavelength dispersion value at the wavelength of said lightwave signal is a normal dispersion value.