| 摘要 |
PURPOSE:To provide the optical communication transmission system at a low cost in which the production of a nonlinear effect in an optical fiber is avoided and the transmission range of over 10,000km is attained in the coherent communication. CONSTITUTION:A CPFSK optical signal subjected to phase modulation by a 5Gb/s signal being an output of an optical transmitter 3 is amplified by nearly +6dBm at an optical fiber amplifier 11 and the amplified signal is inputted to an optical fiber 101 being a 1st transmission line. The total length of the optical fiber 101 is nearly 100km and a fiber having a negative dispersion with respect to a signal optical wavelength. The signal light is amplified by nearly +6dBm at a 2nd optical amplifier repeater 12 and is inputted to an optical fiber 111 being a 2nd transmission line having a negative dispersion characteristic. Thus, the optical amplifier repeater and the optical multi-stage amplifier relay system whose length is 10,000km comprising a negative dispersion optical fiber are built up. The total transmission line dispersion is compensated by a delay equalizer 301 at an intermediate frequency band to equalize the dispersion in the transmission line at the receiver side. |
